Propylene Glycol Methyl Ether Research Articles

Chemically activated Ag-embedded bridged-layer for copper pattern addition on PET film

This article describes a chemically activated method for copper addition on polyethylene terephthalate (PET) films with robust reliability and easy process. Thereof, a bridging layer produced by compatible composite of inorganic AgNO3 and organic epoxy resin (ER) in propylene glycol methyl ether (PM) solvent, was coated on the PET. It was chemically activated when immersed in acetone reagent and sodium borohydride solution, and accordingly the AgNO3 was reduced into Ag monomers as copper catalysts in the next chemical deposition procedure. The as-catalyzed Ag dot is embedded in the bridging layer and thus weaken the interface incompatibility between organic bridging layer and the next deposited metal copper layer. In the chemical plating process, a copper thickness of about 1.5 μm was achieved after 45 min’s plating. Reliability tests that the plated samples were bended by 5000 times at 5-mm and 2-mm radius, were carried out. The results showed the copper layer's resistivity was 0.5 and 0.65 times increasing respectively, in comparison with its originated property and it therefore exhibits excellent fatigue resistance.

Synthesis of Propylene Glycol Methyl Ether Acetate: Reaction Kinetics and Process Simulation Using Heterogeneous Catalyst

Propylene glycol methyl ether acetate (PGMEA) serves as a crucial solvent in semiconductor and display material processes, demanding high purity and low acidity. Despite its significance, its conventional synthesis method using homogeneous catalysts requires extensive purification. Our study explores the use of Amberlyst-15, a stable solid catalyst, to streamline this process. Through batch reactions with a 1:1 reactant ratio at various temperatures and modeling using an integrated reaction rate equation, we obtained kinetic parameters. These parameters were used to predict the kinetics under different reactant ratios and different catalyst amounts, and the predictions match well with experimental results, especially when we used the catalyst amount scaled by the amount of the limiting reactant (PGME) rather than the total amount of the reactants. This highlights the importance of reporting kinetic parameters with proper scaling for catalyst used. Furthermore, we integrated these parameters into process simulations to determine the length of a plug flow reactor (PFR), constructed a PFR system, and confirmed that the simulation results matched well with experimental data obtained from the PFR system. Our findings suggest Amberlyst-15’s potential in simplifying PGMEA synthesis, promising advancements in industrial applications.

Analysis of factors affecting the formation characteristics of carbon dioxide hydrates in pure water system

As the oilfield fully enters the late stage of exploitation, the water content in the oil and gas transportation pipelines is rising. Meanwhile, the high-pressure and low-temperature environment inside the pipeline facilitate the formation of hydrates, which will seriously block the mixing pipeline and cause a series of production safety problems. Therefore, it is necessary to control the risk under the high water content system. In this paper, a high-pressure flow loop device with a viewable window was used to study the formation characteristics of carbon dioxide hydrate in a pure water system, and the effects of the liquid loading, pressure, volume flow rate, and two inhibitors, polyvinylpyrrolidone (PVP) and propylene glycol methyl ether (PM), on the induction time of carbon dioxide hydrate formation were investigated. The experimental results showed that the amount of liquid loading, pressure, volume flow rate, and inhibitor had a significant effect on the hydrate induction time. In addition, the ether compounds PM and PVP have inhibitory synergistic effects, which can significantly prolong the hydrate induction time, and the inhibitory synergistic effect is further enhanced with the increase of PM concentration, which further suggests the synergistic inhibition mechanism of the two. Based on the standard regression coefficient method, the factors affecting the induction time were subjected to sensitivity analysis, and it was found that the inhibitor was the most important factor affecting the induction time. Therefore, future research should also focus on finding better performance of inhibitors, synergists and their ratio.

Density, viscosity, excess properties, and intermolecular interaction of propylene glycol methyl ether + 1,2-propylenediamine binary system

In this work, the systematic measurements of physicochemical properties, viz., density (ρ) and viscosity (η) values of propylene glycol methyl ether (PGME) + 1,2-propylenediamine (1,2-PDA) binary system, including pure substances, over the entire mole fraction range at the temperatures of T/K = (298.15 to 318.15) under atmospheric pressure of P = 100.5 kPa. The fundamental data were used to calculate several excess properties, including excess molar volume (VmE), viscosity deviation (Δη), and excess activation Gibbs free energy (ΔG∗E). Meanwhile, the work further investigated the values of thermal expansion coefficient (αp), partial molar volume (V¯) and apparent molar volume (Vφ), thereby offering a comprehensive understanding on non-ideal behavior of the binary system. Furthermore, the variations in ρ values with various molar ratios and temperatures were evaluated through Jouyban-Acree model and nonlinear least squares method. Simultaneously, Grunberg-Nissan model, Eyring-Margules model, Heric model, and McAllister model, were used to fit the dependence of η values on the molar ratio. Arrhenius equation was employed to fit the temperature dependency of η values. In addition, Redlich-Kister (R-K) equation was utilized to fit the VmE, Δη, and ΔG∗E values of binary system. Based on spectral analyses of Raman, ultra-violet (UV), and 1H Nuclear Magnetic Resonance (NMR) and density functional theory (DFT) calculation, the intermolecular hydrogen bond (IHB) of PGME with 1,2-PDA was discussed in depth.

Adjustable photovoltaic performance driven by polarization in molecular ferroelectrics

The photovoltaic effect driven by ferroelectric polarization shows great application potential in photovoltaic devices. Two-dimensional (2D) Ruddlesden-Popper perovskite molecular ferroelectric materials, which combine polarization and low band gap properties, occupy a promising position in this field. However, literature reports mostly focus on single crystal blocks, and film devices are rarely reported. In this paper, 2D EA4Pb3Br10 (EA=ethylammonium) molecular ferroelectrics are used as the absorption layers to prepare photovoltaic devices, and the photovoltaic performance of the devices is enhanced by polarization. Dense EA4Pb3Br10 films are prepared by immediately adding antisolvent propylene glycol methyl ether acetate when the spin coating rate reaches the maximum. Surprisingly, the photovoltaic device exhibits significant photovoltaic effects under AM1.5 (100 mW/cm2) illumination with VOC ∼ 1.042 V and JSC ∼ 438.02 μA/cm2, which is much higher than that of ordinary inorganic ferroelectrics. In addition, the photovoltaic performance has been greatly improved by applying an external electric field, reaching to the maximum VOC ∼ 1.087 V and JSC ∼ 489.12 μA/cm2. This indicates the potential application prospects of 2D EA4Pb3Br10 molecular ferroelectric films in photovoltaic devices.

Molybdenum-Containing Dendritic Mesoporous Silica Nanospheres as Effective Catalysts for Synthesis of Propylene Glycol Methyl Ether Acetate

Molybdenum-Containing Dendritic Mesoporous Silica Nanospheres as Effective Catalysts for Synthesis of Propylene Glycol Methyl Ether Acetate

Lipopolysaccharide stimulates macrophages to secrete exosomes containing miR-155-5p to promote activation and migration of hepatic stellate cells

To observe the effect of exosomes secreted by lipopolysaccharides (LPS)-stimulated macrophages on hepatic stellate cell activation and migration and explore the underlying molecular mechanism. Human monocyte THP-1 cells were induced to differentiate into macrophages using propylene glycol methyl ether acetic acid (PMA, 100 ng/mL, 24 h) followed by stimulation with LPS, and the culture supernatant of macrophages was collected for extraction of the exosomes by ultracentrifugation. The expression of miR-155-5p in the exosomes was detected using qRT-PCR. A Transwell co-culture system was used to observe the effects of the macrophage-derived exosomes on LX2 cell (a hepatic stellate cell line) proliferation, migration, oxidative stress and the expression of fibrosis biomarkers, which were also observed in LX2 cells transfected with miR-155-5p-mimics or miR-155-5p-inhibitors. Western blotting was used to detect the expressions of SOCS1 and its downstream signal pathway proteins. Treatment with the exosomes from LPS-stimulated macrophages significantly enhanced the proliferation and migration ability of LX2 cells and increased the levels of oxidative stress and expressions of the fibrosis markers such as type Ⅰ collagen (P < 0.05). The expression of miR-155-5p in the exosomes secreted by macrophages was significantly increased after LPS treatment (P < 0.01). LX2 cells overexpressing miR-155-5p also exhibited significantly enhanced proliferation and migration with increased oxidative stress levels and expression of type Ⅰ collagen (P < 0.05), and interference of miR-155-5p expression produced the opposite effects. Western blotting showed that miR-155-5p overexpression obviously inhibited SOCS1 expression and promoted p-Smad2/3, Smad2/3 and RhoA protein expressions in LX2 cells (P < 0.05). LPS stimulation of the macrophages increases miR-155-5p expression in the exosomes to promote activation and migration and increase oxidative stress and collagen production in hepatic stellate cells.

Predicting human neurotoxicity of propylene glycol methyl ether (PGME) by implementing in vitro neurotoxicity results into toxicokinetic modelling

Although organic solvents have been associated with CNS toxicity, neurotoxicity testing is rarely a regulatory requirement. We propose a strategy to assess the potential neurotoxicity of organic solvents and predict solvent air concentrations that will not likely produce neurotoxicity in exposed individuals. The strategy integrated an in vitro neurotoxicity, an in vitro blood-brain barrier (BBB), and an in silico toxicokinetic (TK) model. We illustrated the concept with propylene glycol methyl ether (PGME), widely used in industrial and consumer products. The positive control was ethylene glycol methyl ether (EGME) and negative control propylene glycol butyl ether (PGBE), a supposedly non-neurotoxic glycol ether. PGME, PGBE, and EGME had high passive permeation across the BBB (permeability coefficients (Pe) 11.0 × 10−3, 9.0 × 10−3, and 6.0 × 10−3 cm/min, respectively). PGBE was the most potent in in vitro repeated neurotoxicity assays. EGME's main metabolite, methoxyacetic acid (MAA) may be responsible for the neurotoxic effects reported in humans. No-observed adverse effect concentrations (NOAECs) for the neuronal biomarker were for PGME, PGBE, and EGME 10.2, 0.07, and 79.2 mM, respectively. All tested substances elicited a concentration-dependent increase in pro-inflammatory cytokine expressions. The TK model was used for in vitro-to-in vivo extrapolation from PGME NOAEC to corresponding air concentrations (684 ppm). In conclusion, we were able to predict air concentrations that would not likely result in neurotoxicity using our strategy. We confirmed that the Swiss PGME occupational exposure limit (100 ppm) will not likely produce immediate adverse effects on brain cells. However, we cannot exclude possible long-term neurodegenerative effects because inflammation was observed in vitro. Our simple TK model can be parameterized for other glycol ethers and used in parallel with in vitro data for systematically screening for neurotoxicity. If further developed, this approach could be adapted to predict brain neurotoxicity from exposure to organic solvents.

Insights into the Structure-Property-Activity Relationship of Zeolitic Imidazolate Frameworks for Acid-Base Catalysis.

Zeolitic imidazolate frameworks (ZIFs) have been extensively examined for their potential in acid-base catalysis. Many studies have demonstrated that ZIFs possess unique structural and physicochemical properties that allow them to demonstrate high activity and yield products with high selectivity. Herein, we highlight the nature of ZIFs in terms of their chemical formulation and the textural, acid-base, and morphological properties that strongly affect their catalytic performance. Our primary focus is the application of spectroscopic methods as instruments for analyzing the nature of active sites because these methods can allow an understanding of unusual catalytic behavior from the perspective of the structure-property-activity relationship. We examine several reactions, such as condensation reactions (the Knoevenagel condensation and Friedländer reactions), the cycloaddition of CO2 to epoxides, the synthesis of propylene glycol methyl ether from propylene oxide and methanol, and the cascade redox condensation of 2-nitroanilines with benzylamines. These examples illustrate the broad range of potentially promising applications of Zn-ZIFs as heterogeneous catalysts.

Simulation and design of a heat-integrated double-effect reactive distillation process for propylene glycol methyl ether production

A double-effect reactive distillation (DERD) process was proposed for the production of propylene glycol methyl ether from propylene oxide and methanol to overcome the shortcoming of low selectivity and high-energy consumption in the tubular plug-flow reactor. A single-column reactive distillation (RD) process was conducted under optimized operating conditions based on sensitivity analysis as a reference. The results demonstrated that the proposed DERD process is able to achieve more than 95% selectivity of the desired product. After that, a design approach of the DERD process with an objective of the minimum operating cost was proposed to achieve further energy savings in the RD process. The proposed DERD configuration can provide a large energy-savings by totally utilization of the overhead vapor steam in the high-pressure RD column. A comparison of the single-column RD process revealed that the proposed DERD process can reduce the operating cost and the total annual cost of 25.3% and 30.7%, respectively, even though the total capital cost of DERD process is larger than that of the RD process.

VOC emitted by biopharmaceutical industries: Source profiles, health risks, and secondary pollution

The biopharmaceutical industry contributes substantially to volatile organic compounds (VOCs) emissions, causing growing concerns and social developmental conflicts. This study conducted an on-site investigation of the process-based emission of VOCs from three biopharmaceutical enterprises. In the workshops of the three enterprises, 26 VOCs were detected, which could be sorted into 4 classes: hydrocarbons, aromatic hydrocarbons, oxygen-containing compounds, and nitrogen-containing compounds. Ketones were the main components of waste gases, accounting for 44.13%–77.85% of the overall VOCs. Process-based source profiles were compiled for each process unit, with the fermentation and extraction units of tiamulin fumarate being the main source of VOC emissions. Dimethyl heptanone, vinyl acetate, diethylamine, propylene glycol methyl ether (PGME), and benzene were screened as priority pollutants through a fuzzy comprehensive evaluation system. Ground level concentration simulation results of the Gauss plume diffusion model demonstrated that the diffusivity of VOCs in the atmosphere was relatively high, indicating potential non-carcinogenic and carcinogenic risks 1.5–2 km downwind. Furthermore, the process-based formation potentials of ozone and secondary organic aerosols (SOAs) were determined and indicated that N-methyl-2-pyrrolidone, dimethyl heptanone, and PGME should be preferentially controlled to reduce the ozone formation potential, whereas the control of benzene and chlorobenzene should be prioritized to reduce the generation of SOAs. Our results provide a basis for understanding the characteristics of VOC emission by biopharmaceutical industries and their diffusion, potentially allowing the development of measures to reduce health risks and secondary pollution.

Supercooling elimination of cryogenic-temperature microencapsulated phase change materials (MPCMs) and the rheological behaviors of their suspension

Phase change materials (PCMs) when amalgamated in a shell material to form microencapsulated-PCMs (MPCMs) usually exhibit high levels of supercooling due to the limited crystallization process. In the present study, various efforts were made to reduce this phenomenon, including increasing the MPCM size, employing nucleating agents, and embedding copper nanoparticles into the MPCM shells. It was observed that with an increase in the microcapsule size from 43 μm to 76 μm, the supercooling was reduced by a value of 10.2 °C from melting/freeing point peak temperature differences of 37.6 to 27.4 for the 1200 rpm and 800 rpm samples respectively. Comparatively, the implementation of octadecanol nucleating agent 30 wt % resulted in a reduction of supercooling by 22.9 °C. The introduction of Cu nanoparticles with a decane core can also reduce the supercooling degree by 4.6 °C, while the thermal conductivity the MPCM samples with a hexadecane core increased from 0.173 to 0.182 W m−1 K−1 before and after the addiction of the Cu nanoparticles. Furthermore, di(propylene glycol) methyl ether was used as a carrier fluid for the MPCMs to study the slurry rheological behaviors with various MPCM compositions. It was observed that the MPCM suspension with 10–20% MPCM mass concentration did not exhibit shear thinning, while the 30% sample conveyed shear thinning properties. Furthermore, near the crystallization temperature of the PCM, the slurry viscosity sharply rose, attributed to the volume changes and non-cooperative motion of MPCM microcapsules.

Inhibition of N-vinylpyrrolidone on hydrate in high-pressure flow system under the synergistic effect of ether compounds

Through the experimental tests as performed on a high-pressure flow loop test bench, the synergistic effect of diethylene glycol monoethyl ether (DEGEE), propylene glycol methyl ether (PM), and ethylene glycol phenyl ether (EPH) on the inhibition of inhibitors on hydrate growth was explored under the same initial temperature (285.15 K), pressure (5.0 MPa) and flow rate (230 L/h). The average particle size, relative inhibition performance factor (RIP), and initial formation rate of methane hydrate in the system with a single kinetic inhibitor (or monoalcohol ether synergistic agent) were obtained by experiments, and compared with the relevant parameters in the system with a kinetic inhibitor and a synergistic agent. The experimental results show that the presence of PVP in the system increases the average particle size, which may be due to the adsorption of kinetic inhibitors on hydrate crystals. When the relative inhibition performance factor was used as the index, all the three kinds of synergistic agents promoted the inhibition performance of PVP. DEGEE had the best promotion effect, EPH was the weaker, and PM was the weakest. The synergistic agents in the composite system had little effect on the initial formation rate of hydrate. The addition of kinetic inhibitors and synergistic agents would transform the hydrate formation medium from the wall to the gas–water interface, while the presence of the oil phase in the system significantly weakened the inhibition performance in the kinetic inhibitor-synergist system. The results and theories obtained in this experiment can provide a theoretical basis for the flow guarantee in actual pipelines.

Preparing and applying a poly(styrene-co-maleic anhydride)-g-polyetheramine hyperdispersant

Purpose The purpose of this study was the preparation of a poly(styrene-co-maleic anhydride)-g-polyetheramine (SMA-g-PEA) hyperdispersant that reduces the viscosity of the system and improves the colouring intensities of pigments. Design/methodology/approach PEA of specific quality was dissolved in propylene glycol methyl ether. SMA was then added according to the required mass ratio. The solution was refluxed for 10 h under a stream of protective N2. The prepared hyperdispersant was then characterised by Fourier-transform infrared, UV–visible and 1H NMR spectroscopies, gel-permeation chromatography and thermogravimetry. Findings PEA was successfully grafted onto the SMA polymer and the synthesised product was found to be thermally stable. The copolymer with a 6:1 mass ratio is the best dispersant and was used to disperse carbon black, phthalocyanine blue and permanent violet in water-based systems, which helps to improve the application performance of each pigment by reducing the viscosity of the system and improving the colouring intensity of the pigment. The water dispersion is stable and does not exhibit an increase in viscosity after seven days of oven aging at 50°C. Originality/value SMA-g-PEA water-based hyperdispersants were successfully synthesised. The prepared hyperdispersants help to improve the application performance of each studied pigment by reducing the viscosity of the system and improving the colouring intensity of the pigment.

Solvent recovery from photolithography wastes using cellulose ultrafiltration membranes

Solvent recycling and reuse are indispensable for ensuring a sustainable chemical industry and circular economy. In this study we report the fabrication of cellulose ultrafiltration membranes and their application in recovery of propylene glycol methyl ether acetate (PGMEA) used as developer solvent in SU-8 photolithography. Cellulose membranes were fabricated via alkaline hydrolysis of cellulose acetate membranes in aqueous NaOH. Membrane permeance and molecular weight cut-off (MWCO) were tuned via changing cellulose acetate concentration in precursor solution and evaporation of volatile co-solvent, acetone. MWCO of the membranes was found to be smallest in DMSO, followed by water and largest in methanol. The difference was attributed to the different hydrodynamic diameters of the probe molecules in these solvents. SU-8 rejection from its representative developer solutions in PGMEA was assessed in dead-end filtration at up to 80% permeate recovery. After the first filtration, the collected permeate was fed to the same membrane to simulate a two-stage filtration scenario. Rejection was in the range of 87%–89% in a first stage filtration and 79%–80% in a second stage, both operated at 80% permeate recovery. Recycled solvent could be used in photolithography although with some loss of pattern fidelity, possibly owing to remaining SU-8 and photoacid generator in PGMEA. • Cellulose membrane permeance and MWCO tuned between 0.40–23.3 LHM/bar and 4–15 kDa. • Permeance is via pore flow mechanism but is also affected by swelling and steric hindrance. • SU-8 can be recovered from its PGMEA solution and reused in photolithography.

Energy-saving reactive pressure-swing distillation process for separation of methanol - dimethyl carbonate azeotrope via reacting with propylene oxide

Pressure-swing distillation (PSD) is a widely used in the chemical industry to separate azeotropes without the introduction of a any third component; however, the process involves high energy consumption and operating costs are required owing to the change in pressure. For the separation of methanol–dimethyl carbonate azeotropes, an intensified reactive pressure-swing distillation (R-PSD) process has been proposed, wherein a reactive distillation column is used, instead of a high-pressure column, and the propylene oxide (PO) is introduced into the system as a reactant to reacts with methonal. To compare the feasibility of the proposed R-PSD process with the conventional heat-integrated PSD process, three indicators—total energy requirements, total annual cost, and CO2 emissions—were used. The results show that the R-PSD process performs better than the conventional heat-integrated PSD process in terms of energy, economics and environmental owing to the partial consumption of methanol and the simultaneous co-production of high-value propylene glycol methyl ether (PGME). Moreover, at 50% methanol consumption, the total energy consumption, total annual cost, and the CO2 emissions were reduced by 46.0%, 34.3%, and 45.0%, respectively, compared with the conventional heat-integrated PSD process. This implies the improved R-PSD process has significant energy-saving potential.

Evaluation of propylene glycol methyl ether as a potential challenge agent for leak detection of liquid and headspace from closed system drug transfer devices using Fourier transform infrared spectroscopy.

Choosing an appropriate surrogate of hazardous drugs for use in testing Closed System Drug-Transfer Devices (CSTDs) is a challenging endeavor with many factors that must be considered. It was suggested that the compound propylene glycol methyl ether (PGME) may meet many of the criteria we considered important in a suitable surrogate. Criteria included sufficient volatility to evaporate from aqueous liquid leaks efficiently, a Henry's constant which produced sufficient vapor phase concentrations to make headspace leaks detectable, and suitability for detection using a low-cost detection system. We evaluated the measurement of vapors from solutions containing PGME released inside a closed chamber. We present data used to quantify limits of detection, limits of quantification, bias, precision, and accuracy of Fourier Transform Infrared Spectroscopy (FTIR) measurements of vapors from 2.5 M PGME solutions. The effects of ethanol as a component of the PGME solution were also evaluated. Liquid drops of PGME solutions and headspace vapors above PGME solutions were released to simulate leaks from CSTDs. Using a calibration apparatus, an instrumental limit of detection (LOD) of 0.25 ppmv and a limit of quantitation (LOQ) of 0.8 ppmv were determined for PGME vapor. A LOD of 1.1 μL and a LOQ of 3.5 μL were determined for liquid aliquots of 2.5 M PGME solution released in a closed chamber. Accurate quantitation of liquid leaks required complete evaporation of droplets. With the upper end of the useable quantitation range limited by slow evaporation of relatively large droplets and the lower end defined by the method LOQ, the method evaluated in this research had a narrow quantitative range for liquid droplets. Displacement of 45 mL of vial headspace containing PGME vapor is the largest amount expected when using the draft NIOSH testing protocol. Release of an unfiltered 45 mL headspace aliquot within the NIOSH chamber was calculated to produce a concentration of 0.8 ppmv based on the Henry's constant, which is right at the instrumental LOQ. Therefore, the sensitivity of the method was not adequate to determine leaks of PGME vapor from a headspace release through an air filtering CSTD when using the draft NIOSH testing protocols with an FTIR analyzer.

Synergistic effects of frothers, collector and salt on bubble stability

This work investigates synergistic and antagonistic effects of flotation reagents and salt on the air–liquid interface and stability of air bubbles under quasi-static conditions. Frothers of different families (aliphatic alcohol, polypropylene glycol and propylene glycol methyl ether), potassium amyl xanthate (PAX), a common collector used in the flotation of sulphide minerals, and sodium chloride (NaCl) were employed in the study. Adsorption of frother and collector molecules from individual and mixed solutions was studied through surface tension and Quartz Crystal Microbalance with Dissipation (QCM–D) measurements, while bubble stability was examined by the coalescence time of the bubble pairs in these solutions. The results show that NaCl enhanced the adsorption of frothers, while PAX's impact on the adsorption of the frother was found to be rather insignificant compared to the salt. The bubble coalescence time measurements, however, pointed to a significant synergistic effect between PAX and two frothers i.e., Methyl Iso Butyl Carbinol (MIBC) and Di Propylene Glycol (DPG) as reflected in the improvement of bubble stability. In the ternary solution systems (frother/NaCl/PAX), the concentration of salt in the MIBC mixture solution was found to have an opposite impact on the bubble lifetime in the DPG and DPM solutions. For instance, bubble lifetime increased with higher NaCl concentrations added to the DPG and DPM solutions, whereas it decreased in the MIBC solutions.

Comparative Study of Microwave Oven-Assisted Tissue Processing with Isopropanol and Mineral Oil Mixture and Propylene Glycol Methyl Ether on Morphological Quality of Tissue Sections

Background: &#x0D; Over several years, xylene has been traditionally utilised as the clearing agent of choice in tissue-processing due to effectiveness in rapidly clearing tissue, facilitating the paraffin infiltration process. However, xylene use adversely impacts the health of personnel with long term exposure due to toxicity. In order to overcome these effects and replace it with a safer alternative agent, the present study aims to compare quality of tissue sections processed using an isopropanol and mineral oil mixture and propylene glycol methyl ether (PGME) as xylene substitutes.&#x0D; &#x0D; Methods: &#x0D; Rat skeletal muscle tissue samples (n=20) were prepared for each processing protocol with xylene substitutes. Tissue specimens were processed according to the proposed microwave protocol. The clearing steps were performed using isopropanol and mineral oil mixture, and PGME, replacing xylene. From each paraffin-embedded block, one section of 4-5µm thickness tissue was obtained and conventionally-stained with Haematoxylin and Eosin (H&amp;E). The histological sections were microscopically assessed and scored by a pathologist. A qualitative analysis was performed with the results obtained.&#x0D; &#x0D; Results: &#x0D; The overall score obtained for xylene processed tissue was 100% with a score of 2 for all the 3 parameters assessed. However, the outcome for tissue processed with isopropanol and mineral oil mixture was 28.6% unsatisfactory, 28.6% satisfactory and 42.8% good. In PGME-treated tissues, 14.3% were unsatisfactory sections, 71.4% were satisfactory and 14.3% produced good quality sections. Overall, tissues processed using both substitutes exhibited sufficient staining quality in terms of the aforementioned parameters as compared to xylene-processed tissues, though significant difference in scores were observed.&#x0D; &#x0D; Conclusion:&#x0D; Despite several challenges faced in the study, isopropanol and mineral oil mixture and PGME can be suggested as alternative clearing agents to xylene, provided having access to a more sophisticated microwave oven with precise temperature control for complete tissue-processing.

Novel sampling strategy for alive animal volatolome extraction combined with GC-MS based untargeted metabolomics: Identifying mouse pup pheromones

In this study, we identify 11 mouse pup volatiles putatively involved in maternal care induction in adult females. For this purpose, we have adapted the dynamic headspace methodology to extract the volatolome of whole alive animals. Untargeted metabolomic methodology was used to compare the volatolome of neonatal (4–6 days) with elder pups until the age of weaning (21–23 days old). Pup volatolome was analyzed by gas chromatography (GC) coupled to single quadrupole mass spectrometry (MS) using automated thermal desorption for sample introduction. After data processing and multivariate statistical analysis, comparison with NIST spectral library allowed identifying compounds secreted preferentially by neonatal pups: di(propylen glycol) methyl ether, 4-nonenal, di(ethylene glycol) monobutyl ether, 2-phenoxyethanol, isomethyl ionone, tridecanal, 1,3-diethylbenzene, 1,2,4,5-tetramethylbenzene, 2-ethyl-p-xylene and tri(propylene glycol) methyl ether. Palmitic acid was enriched in the volatolome of fourth week youngsters compared to neonatal pups. The results demonstrated the great potential of the new sampling procedure combined with GC-MS based untargeted volatolomics to identify volatile pheromones in mammals.