Chemical Loading Research Articles

The role of biologization of processes in increasing the technological and economic efficiency of viticulture

The necessity of increasing the technological and economic efficiency of viticulture is substantiated. The assessment of the influence of negative manifestations of chemical and technogenic intensification factors in viticulture on the stability of agrocenoses with the participation of grape plantations is given. The priority role of biotechnologies in ensuring the stability of grape agrocenoses to negative manifestations caused by an increase in chemical and man-made loads, which are a set of industrial methods that use living organisms and biological processes for the production of industrial products, is substantiated. The basic principles on which the biologization of protective measures of vineyards is based are considered. The effectiveness of the main methods of biological protection of industrial vineyards is assessed, the use of which will reduce the negative impact of xenobiotics on the environment, material costs for the purchase of insecticides in the cultivation of products and ensure the development of optimal agrotechnological solutions for the protection of perennial plantations, which will contribute to the growth of technological and economic efficiency of industrial production.

Altered Transcriptome Response in PBMCs of Czech Adults Linked to Multiple PFAS Exposure: B Cell Development as a Target of PFAS Immunotoxicity.

While the immunomodulation effects of per- and polyfluoroalkyl substances (PFASs) are described on the level of clinical signs in epidemiological studies (e.g., suppressed antibody response after vaccination), the underlying mechanism has still not been fully elucidated. To reveal mechanisms of PFAS exposure on immunity, we investigated the genome-wide transcriptomic changes of peripheral blood mononuclear cells (PBMCs) responding to PFAS exposure (specifically, exposure to PFPA, PFOA, PFNA, PFDA, PFUnDA, PFHxS, and PFOS). Blood samples and the chemical load in the blood were analyzed under the cross-sectional CELSPAC: Young Adults study. The overall aim of the study was to identify sensitive gene sets and cellular pathways conserved for multiple PFAS chemicals. Transcriptome networks related to adaptive immunity were perturbed by multiple PFAS exposure (i.e., blood levels of at least four PFASs). Specifically, processes tightly connected with late B cell development, such as B cell receptor signaling, germinal center reactions, and plasma cell development, were shown to be affected. Our comprehensive transcriptome analysis identified the disruption of B cell development, specifically the impact on the maturation of antibody-secreting cells, as a potential mechanism underlying PFAS immunotoxicity.

Study of the structure of yttrium-based nanoporous ceramic materials

Porous ceramic materials with high filtration performance are widely used in conditions of high chemical, thermal and radiation loads. The results of studying the structure and morphology of the pore space of ceramic membranes are presented. Ultradispersed refractory powder Y2O3 was used as a main component-filler. The synthesis was carried out using compaction, technological combustion and self-propagating high-temperature synthesis. The use of ultradisperse sintering additives with highly developed surface (MgO — 5 μm, SiC — 3, SiO2 — 5 μm) allowed us to ensure the energy efficiency of synthesis of high- porous ceramic materials at low temperatures. Analysis of the structure and pore space using mercury porometry and alternative methods showed that the average pore size in the synthesized 3D matrix composite material based on yttrium orthosilicate matrix with yttrium oxide filler is 1.1 μm, the equivalent hydraulic pore diameter being about 100 nm. The difference is attributed to the variability of cross sections and high tortuosity of pore channels. Since the density of the material is 2.3 g/cm3 and the compressive strength is about 2 MPa, it can be easily machined with carbide tools being a promising material for manufacturing products with complex shapes. The obtained results can be used in developing energy-efficient technologies of one-stage production of yttrium oxide-based filters with high porosity to be used under conditions of exposure to radiation, aggressive media and high temperatures.

An eco-friendly versatile superabsorbent hydrogel based on sodium alginate and urea for soil improvement with a synchronous chemical loading strategy

In this paper, an eco-friendly versatile superabsorbent material was designed for soil improvement, and a synchronous chemical loading strategy was proposed. In this strategy, urea not only acted as fertilizer but also acted as a crosslinker to construct an alginate network. The microstructure, chemical structure, thermal stability and composition of the obtained SA/urea hydrogel were characterized in detail. Adsorption behavior and application performance in agriculture were evaluated. The results demonstrated that urea had two different conformations in the network. The SA/urea hydrogel had abundant pore structures with excellent water absorption performance. It could not only improve the water retention capacity of soil but also release nitrogen, phosphorus and potassium elements with degradation for as long as 9 weeks. Moreover, the hydrogel could promote plant growth, increase the nutritional composition of plants and inhibit the accumulation of harmful nitrate in plants. With advantages, including biodegradability, high water absorption, controllable degradation, excellent water retention, sustained NPK release and improved plant nutrition value, the SA/urea hydrogel has great potential for soil improvement in agriculture as an eco-friendly versatile water retention agent and can be expected to extend to more fields as a novel superabsorbent material.

Chemical Activity-Based Loading of Artificial Sediments with Organic Pollutants for Bioassays: A Proof of Concept.

Persistent organic pollutants (POPs) pose a risk in aquatic environments. In sediment, this risk is frequently evaluated using total or organic carbon-normalized concentrations. However, complex physicochemical sediment characteristics affect POP bioavailability in sediment, making its prediction a challenging task. This task can be addressed using chemical activity, which describes a compound's environmentally effective concentration and can generally be approximated by the degree of saturation for each POP in its matrix. We present a proof of concept to load artificial sediments with POPs to reach a target chemical activity. This approach is envisioned to make laboratory ecotoxicological bioassays more reproducible and reduce the impact of sediment characteristics on the risk assessment. The approach uses a constantly replenished, saturated, aqueous POP solution to equilibrate the organic carbon fraction (e.g., peat) of an artificial sediment, which can be further adjusted to target chemical activities by mixing with clean peat. We demonstrate the applicability of this approach using four polycyclic aromatic hydrocarbons (acenaphthene, fluorene, phenanthrene, and fluoranthene). Within 5 to 17 weeks, the peat slurry reached a chemical equilibrium with the saturated loading solution. We used two different peat batches (subsamples from the same source) to evaluate the approach. Variations in loading kinetics and eventual equilibrium concentrations were evident between the batches, which highlights the impact of even minor disparities in organic carbon properties within two samples of peat originating from the same source. This finding underlines the importance of moving away from sediment risk assessments based on total concentrations. The value of the chemical activity-based loading approach lies in its ability to anticipate similar environmental impacts, even with varying contaminant concentrations. Environ Toxicol Chem 2024;43:279-287. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Groundwater dynamics in intertidal zones of beach aquifers during salt-fingering flow

At aquifer-sea interfaces, submarine groundwater discharge (SGD) and related chemical loads are closely related to groundwater environment in the intertidal zone of coastal aquifers. Although unstable salinity distribution in the intertidal zone associated with salt-fingering flow has been known as a natural phenomenon for some coastal aquifers, a quantitative understanding of groundwater dynamics in the intertidal zone during salt-fingering flow is still lacking. This study investigated the movement features of salt fingers and the response laws of freshwater discharge zone (FDZ) in the intertidal zone, considering the fixed and seasonal inland conditions. The results revealed that during salt-fingering flow, the finger was repeatedly generated and detached from the intertidal zone. Horizontally, the finger moved toward the sea, and the finger speed first increased at the development stage, then remained unchanged at the separation stage, and finally decreased at the mergence stage. The movement speed of salt fingers was closely related to ambient freshwater flow in the FDZ. In the vertical direction, the finger first permeated downward with a decreasing speed, and then the upward discharge of fresh groundwater in the FDZ region with an increased flow velocity pushed the finger upwards with an increasing speed. In contrast to the results in a stable intertidal regime, the width of FDZ at the aquifer-sea interface fluctuated over time, and the variation trends possessed a well agreement with the flux of fresh groundwater discharge. This suggested that the width of FDZ at the aquifer-sea interface can be used as an indicator of fresh groundwater discharge, even in an unstable regime, to provide a basis for field monitoring. The intensity of salt-fingering flow varied over time under the condition of seasonal freshwater inflow. The mean duration of salt fingers decreased slightly with the increase of seasonal freshwater periods due to a decrease in the interface perturbation for the intertidal environment. These findings lay the foundation for gaining a better understanding of the potential implications of salt-fingering flow on SGD and related solute transports.

Protein Nanotubes as Advanced Material Platforms and Delivery Systems.

Protein nanotubes (PNTs) as state-of-the-art nanocarriers are promising for various potential applications both in the food and pharmaceutical industries. Derived fromedible starting sources like α-lactalbumin, lysozyme, and ovalbumin, PNTs bear properties of biocompatibility and biodegradability. Their large specific surface area and hydrophobic core facilitate chemical modification and loading of bioactive substances, respectively. Moreover, their enhanced permeability and penetration ability across biological barriers such as intestinal mucus, extracellular matrix, and thrombus clot, make it promising platforms for health-related applications. Most importantly, their simple preparation processes enable large-scale production, supporting applications in the biomedical and nanotechnological fields. Understanding the self-assembly principles is crucial for controlling their morphology, size, and shape, and thus providesthe ground to a multitude of applications. Here, the current state-of-the-art of PNTs including their building materials, physicochemical properties, and self-assembly mechanisms are comprehensively reviewed. The advantages and limitations, as well as challenges and prospects for their successful applications in biomaterial and pharmaceutical sectors are then discussed and highlighted. Potential cytotoxicity of PNTs and the need of regulations as critical factors for enabling in vivo applications are also highlighted. In the end, a brief summary and future prospects for PNTs as advanced platforms and delivery systems are included.

Di-aldehyde tunicate cellulose nanocrystal (D-tCNC) aerogels for drug delivery: Effect of D-tCNC composition on aerogel structure and release properties

Aerogels as drug carriers have the characteristics of a large specific surface area, high porosity and an elastic skeleton structure. Compared with traditional drug carriers, the use of aerogels as drug carriers can avoid the complexity of drug delivery and improve the efficiency of drug loading. In this work, the oxidation of tunicate cellulose nanocrystals (tCNCs) with NaIO4 was used to prepare di-aldehyde tunicate cellulose nanocrystals (D-tCNCs). Tetracycline (TC) was used as a drug model and pH-responsive drug-loaded aerogels were prepared by the Schiff base reaction between TC and the aldehyde group on D-tCNCs. The chemical structure, crystallinity, morphology, compression properties, porosity, swelling rate and drug loading properties were investigated by FT-IR, XRD, SEM and universal testing machines. The results showed that the porosity and equilibrium swelling ratio of the D-tCNC-TC aerogels were 95.87 % and 17.52 g/g, respectively. The stress of the D-tCNC-TC aerogel at 15 % compression was 0.07 MPa. Moreover, the analysis of drug-loaded aerogels indicated that the drug loading and encapsulation rates of D-tCNC-TC aerogels were 16.86 % and 78.75 %, respectively. In in vitro release experiments, the cumulative release rate of drug-loaded aerogel at pH = 1.2 and pH = 7.4 was 87.5 % and 79.3 %, respectively. These results indicated that D-tCNC-TC aerogels have good drug loading capacity and are pH-responsive in the pH range of 1.2 to 7.4. The prepared D-tCNC-TC aerogels are expected to be applied in drug delivery systems.

An effective stress-based approach to modeling the chemo-mechanical behavior of saturated active clay

Pore water chemistry can exert significant controls over the chemo-mechanical behavior of chemically active soils, which has not been characterized by using the traditional Terzaghi’s effective stress to a satisfactory extent. In this paper, based on the concept of intergranular stress, a generalized effective stress for saturated active soils is reconceptualized and incorporated into the framework of the modified Cam–Clay (MCC) model to describe the mechanical response of soils upon complex chemical and mechanical loadings. The proposed model is capable of capturing very well the diverse features of the chemo-behavior of saturated active soils, while inheriting all the advantages of the MCC model, by introducing only one additional parameter. Within this context, a simple equation is derived to predict the development of swelling pressure with the variation of pore water chemistry. It is shown that the proposed swelling-pressure equation predicts very well the development of swelling pressure for expansive soils with a dilute pore solution, though discrepancy appears at high concentration. Because the double layer of clay particles is severely suppressed at high salt concentration, the microfabric of soil can be significantly changed, pointing to the importance of taking into account the effect of soil fabric in the constitutive modeling of active soils with high pore water concentration.

Curcumin-loaded high internal phase emulsions alleviated dextran sulfate sodium-induced ulcerative colitis in mice via inhibiting inflammatory response and modulating gut microbiota

Curcumin is a polyphenol compound that presents an anti-colitis effect. However, oral curcumin exhibits limited in vivo biological efficacy, which may be solved by the use of high internal phase emulsions (HIPEs) that show remarkable abilities: bioactive compounds delivery, high chemical stability and loading capacity, as well as controlled release, etc. The objective of this study was to investigate the preventive effect of curcumin-loaded HIPEs using a dextran sulfate sodium (DSS)-induced colitis C57BL/6J mice model. After 30 mg/ml DSS treatment, all mice exhibited weight loss and shortening of colon tissues to different extents. Compared to the DSS group, the disease activity index and weight loss were considerably suppressed in the curcumin-loaded corn oil and curcumin-loaded HIPEs groups. These groups also exhibited reduced colonic crypt damage, mucosal inflammation and cellular infiltration in the histopathological sections of the colon. Dietary curcumin-loaded HIPEs inhibited the inflammatory response via reducing the contents of inflammatory factors (IL-6, TNF-α and IL-1β) and increasing the content of anti-inflammatory factor (IL-10) significantly. And the relative abundances of Firmicutes and Bacteroidetes were highly reduced and increased, respectively. These findings provide insights into expanding the utilization of curcumin and HIPEs in food systems for the treatment of colon inflammation and related diseases.

A novel approach for in-situ characterization and probabilistic prediction of cutting tool fatigue in machining of Ti-6Al-4V

The wear behavior of cutting tools is highly complex due to combined thermal, mechanical, and chemical loads. As a result, most current tool-wear prediction methodologies are either empirical or highly oversimplified analytical or numerical models of stable abrasive and diffusive wear mechanisms. To predict the complex physics of catastrophic tool edge chipping, which in practice bounds feasible process parameters, this manuscript presents a novel approach for in-situ characterization of tool edge fatigue loads and probabilistic prediction of the likelihood of time to fracture. The results of the analysis suggest encouraging possibilities for more physics-informed and data-driven process design.

Studying the mechanical properties of the mandible and injury prediction under the effect of ossification factors

Background and objectiveIt is essential to know the quantitative interactions between biological tissues and external mechanical and chemical stimuli. This assists the physicians to better know the quantitative behavior of the tissue and plan more effective therapy. In the literature, the effect of the chemical and mechanical loading was investigated on the bone biological cell activities and some mechanical features, but a lack of prediction of bone injury under the chemical and mechanical factors was sensed. Therefore, the present study aims to investigate the effects of the application of major chemical factors involved in ossification, including RANKL11Receptor Activator of Nuclear Factor Kappa Beta Ligand. (Receptor Activator of Nuclear Factor Kappa Beta Ligand), PTH22Parathyroid Hormone. (Parathyroid Hormone), and OPG33Osteoprotegerin. (Osteoprotegerin) on the mandibular bone biological osteoblast and osteoclast activities and mechanical properties. Moreover, the study assesses the bone injury possibility under uniform mastication pressure applied on the premolar tooth in terms of the mechanostat theory undergoing the effects of the chemical factors. MethodsA 3D geometry of the mandible-tooth assembly was generated from the CT image dataset. The geometry was next purified, solidified, and exported to FEM44Finite Element Method. (Finite Element Method) software to be meshed, where boundary conditions and loading were applied. Moreover, the mathematical system of differential equations to model the chemical factor effects on osteoblast and osteoclast activities as well as bone matrix volume fraction and elastic stiffness relations were applied. Next, the values of the equivalent strain were calculated to predict the injury states of the bone. ResultsThe results complied with the literature data. The results showed that RANKL and PTH increased the values of the equivalent strain from 450 με to 11500 με, while OPG reduced that from 450 με to 300 με. ConclusionsTherefore, RANKL and PTH doses of this study put the bone at risk of injury compared to the baseline of no dose applied, while OPG secured the bone from injury.

Valorization of Different Dairy By-Products to Produce a Functional Dairy–Millet Beverage Fermented with Lactobacillus paracasei as an Adjunct Culture

Fermented dairy products not only have a long shelf-life but also have beneficial nutritional values. The products are deficient in dietary fiber and certain bioactive compounds. Adding grains to dairy products is a widespread practice to improve the nutritional and economic aspects. In this work, we studied the effect of fermented millet–milk beverages (FMBs) using pearl millet grains and three different dairy by-products (sweet whey, sweet buttermilk, and skimmed milk). A control treatment prepared with water was also manufactured for comparison. Samples were continuously prepared and fermented using a commercial yogurt starter culture (YC-381) containing L. delbrueckii subsp. bulgaricus, Streptococcus thermophilus, and a pure strain of L. paracasei subsp. Paracasei. Four FMBs (water based: WB-FMB, whey based: WHB-FMB, buttermilk based: BMB-FMB, and skimmed milk based: SMB-FMB) were analyzed during cold storage at 4 °C for up to 15 days for chemical, microbiological properties, minerals content, antioxidant properties, glycemic index, and glycemic load on days 1, 8, and 15. The sensory characteristics of the FMBs were also evaluated during cold storage (4 °C/15 days). In general, the progression of acidity was slower in SMB-FMB and WHB-FMB samples during fermentation compared to in the BMB-FMB sample. The longest fermentation time was for the SMB-FBM sample (3 h), while the shortest was for the BMB-FMB sample (1.5 h). Reflecting the good manufacturing practices, all samples were free of coliform, mold, and yeast. No bacterial growth was detected in the WB-FMB sample at days 8 and 15 of storage, while the growth of Lactobacillus spp. and S. thermophilus was significantly higher (9.97 ± 0.01 and 9.48 ± 0.06, respectively) in the BMB-FMB sample compared to in the other three FMBs. The FMBs produced using dairy by-products had more antioxidant properties. All samples were better perceived during sensory evaluation by panelists than the water-based sample, except for the BMB-FMB sample, in which a bitter taste appeared. In the BMB-FMB sample, the proteolytic degree was significantly higher (4.8 ± 0.09) after 3 h of fermentation by about 460% than in the fresh sample. All samples had a low glycemic index and glycemic load. In addition, acidity progression was slower in SMB-FMB and WHB-FMB samples during fermentation and storage compared to the WB-FMB sample. Therefore, it could be recommended that it is more beneficial to prepare fermented millet–milk beverages using dairy by-products and suitable starter cultures under optimal fermentation conditions instead of using water to maximize the nutritional and economic aspects.

Biological durability and wood–water interactions of sorbitol and citric acid (SorCA) modified wood

This study aimed to investigate the relationship between moisture dynamics of sorbitol and citric acid (SorCA) modified wood and its biological durability. Specifically, the research aimed to determine the chemical loading needed for effective protection against wood-destroying basidiomycetes, while also improving the understanding of the moisture behavior of SorCA-modified wood. The SorCA modification process is relatively new, and thus, there is limited knowledge on its moisture behavior and its impact on biological durability. The research focused on Scots pine sapwood (Pinus sylvestris L.) and used the EN 113-2 standard to investigate its durability against wood-destroying basidiomycetes. Moisture behavior was analyzed through short-term water uptake and release tests, capillary water uptake and CEN/TS 16818. Results showed a significant reduction in liquid and water vapor uptake, likely due to a reduction in the maximum moisture capacity within the wood cell wall. The study confirmed that high chemical loadings (i.e., weight percent gain, WPG) are necessary for adequate decay protection.

Modelling micropollutant cycle in Lake Como in a winter scenario: Implications for water use and reuse, ecosystem services, and the EU zero pollution action plan

The fate and effects of 42 pharmaceuticals was studied in Lake Como (Italy), in wastewater treatment plants delivering water to the lake, in two rivers and in potable water obtained from lake water. Lake Como is one of the deepest and largest lakes in Northern Italy, serving important ecosystem services (i.e., drinking water, recreational, industrial, irrigation uses), some of which are currently at risk giving the current water scarcity and climate change scenarios. The highest concentrations measured in lake water were those of diclofenac, followed by carbamazepine, its metabolite, and clarithromycin. The data measured allowed to calibrate and run a fugacity-based lake model, which showed that the most important chemical load generally comes from the advective water from the north of the lake, rather than from the direct wastewater treatment plant (WWTP) discharges. This indicates that only an important reduction of chemical discharge (reduced use or extensive treatment) at a drainage basin level could significantly reduce concentrations in water. This has strong implications on how to implement the EU zero pollution action plan to significantly improve water ecosystem and human health protection.

Mitochondrial DNA content as a biomarker for oral carcinogenesis: correlation with clinicopathologic parameters.

Mitochondrial genome (mtDNA) exhibits greater vulnerability to mutations and/or copy number variations than nuclear counterpart (nDNA) in both normal and cancer cells due to oxidative stress generated by inflammation, viral infections, physical, mechanical, and chemical load. The study was designed to evaluate the mtDNA content in oral potentially malignant disorders (OPMDs) and oral squamous cell carcinoma (OSCC). Various parameters were analyzed including its variation with human papillomavirus (HPV) during oral carcinogenesis. The present cross-sectional study comprised of two hundred patients (100 OPMDs and 100 OSCCs) and 100 healthy controls. PCR amplifications were done for mtDNA content and HPV in OPMDs and OSCC using real-time and conventional PCR respectively. The relative mtDNA content was assessed quantitatively and it was observed that mtDNA was greater in OSCC (7.60±0.94) followed by OPMDs (5.93±0.92) and controls (5.37±0.95). It showed a positive linear correlation with habits and increasing histopathological grades. Total HPV-positive study groups showed higher mtDNA content (7.06±1.64) than HPV-negative counterparts (6.21±1.29). An elevated mutant mtDNA may be attributed to increased free radicals and selective cell clonal proliferation in test groups. Moreover, sustained HPV infection enhances tumorigenesis through mitochondria mediated apoptosis. Since, mtDNA content is directly linked to oxidative DNA damage, these quantifications might serve as a surrogate measure for invasiveness in dysplastic lesions and typify their malignant potential.

Is constructed wetlands carbon source or carbon sink? Case analysis based on life cycle carbon emission accounting

Constructed wetlands (CWs) are widely used to polish the effluent of wastewater treatment plants and micro-polluted river or lake water. However, the impact of large-scale applications of CWs on carbon emissions is unclear. In this study, the carbon footprints of two full-scale hybrid CWs were determined based on life cycle assessment (LCA). Results showed that the carbon emission of CW ranged from 0.10 to 0.14 kg CO2-eq/m3, and was significantly correlated with the influent chemical oxygen demand loads and electricity consumption. However, CW would approach carbon neutrality during the service period when taking plant carbon sequestration into consideration. Compared with other advanced wastewater treatment technologies, CWs showed significant low-carbon emission and cost-effective benefits. This study clarified the role of CWs in the carbon cycle and would provide guidance for the construction and management of CWs.

Chemical dissolution of minerals in anthracite after supercritical carbon dioxide immersion: Considering mechanical damage and enhanced porosity

Carbon dioxide injection into in-situ coal seams can effectively enhance coalbed methane recovery and promote carbon sequestration, increasing energy production while reducing greenhouse gas emissions. CO2 is prone to exist in a supercritical state in deep coal seams, so it is of great significance to quantitatively describe the mechanical properties damage of coal caused by supercritical carbon dioxide (SC–CO2). Based on the non-equilibrium thermodynamic framework, a nonlinear model of SC–CO2–coal interaction is developed using the special forms of Helmholtz free energy and energy dissipation. Two damage variables are employed to quantify the irreversible degradation induced by chemical reactions and mechanical loads, respectively. The results indicate that the long-term effect of SC-CO2 can increase the porosity of anthracite by approximately 5.49%, but reduce the elastic modulus and strength by about 58% and 56% respectively. The experimental data confirms that the damage model facilitates an analysis of the interplay among SC-CO2 absorption, porosity, elastic modulus and tensile strength of anthracite. The degradation of anthracite mechanical properties is time-dependent, which means that the risk of coal-rock dynamic disasters increases with the passage of CO2 injection time. This work is expected to study the complex multi-field coupling mechanism of SC-CO2 on in-situ coal seams, providing a theoretical basis for guiding CO2 geological sequestration and CO2 enhanced coalbed methane recovery.

An In-Depth Stability Study of the Essential Oils from Mentha × piperita, Mentha spicata, Origanum vulgare, and Thymus vulgaris: The Impact of Thermal and Storage Conditions

In recent years, there has been a growing scientific interest in essential oils due to their therapeutic and aromatic properties and as potential alternative natural additives for use as preservatives or antibiotics. However, the literature lacks a comprehensive understanding of their stability and how their composition and properties change over time under various conditions. Through this paper, we aim to enhance the existing literature by providing deeper insights into the stability of essential oils and the sustainability of chemical composition in a time-based approach under various conditions. Therefore, four essential oils of the Lamiaceae family (Origanum vulgare, Thymus vulgaris, Mentha spicata, and M. x piperita) were evaluated with respect to their chemical variation influenced by several factors, such as thermal and storage conditions. Three types of containers were utilized to store the essential oils, i.e., glass ampoules, glass tubes, and metallic containers with plastic caps, for up to six months in −20 °C, 4 °C, 23 °C (with or without light exposure), 35 °C, and 45 °C. Samples were routinely analyzed by GC-MS and components were subjected to principal component analysis to ascertain whether the identified constituents may be useful in reflecting the stability of the analyzed samples. The main compounds appeared to be more stable, while the degradation of minor constituents (<1.0%) occurred in all four essential oils despite the storage conditions. Overall, apart from a slight variation in the chemical load, essential oils can be considered stable for various applications, especially those stored under low oxygen availability conditions.

Investigation of pull-out characteristics of connections for post-installed rebar utilizing mortar-based binders and chemical adhesives

ABSTRACT In this study, various types of adhesives were tested for their ability to adhere steel reinforcement bars to old concrete during a pull-out test when they were used in connection to a post-installed re-bar. The cylinder samples were 150 mm in diameter and had anchors made of rebar that varied in diameter (8 mm, 10 mm, 12 mm, 16 mm, and 20 mm) and embedded depth (10, 12.5, 15, and 20 times the rebar diameter). In contrast to the control group of (60 Nos.) cast-in-situ rebar concrete specimens, the other samples (240 samples) were post-installed-rebar concrete specimens with various bonding agents, epoxy-based chemical adhesive, vinyl-ester-based chemical adhesive, and cement-based binders (geopolymer mortar, conventional mortar). The results showed that while they all performed better than cement-based mortar-bonded specimens, the use of the epoxy-based chemical adhesive and vinyl-ester-based chemical adhesive pull-out load values were closely related. The anchorage depth and rebar diameter both improve the bond strength which reflects in terms of pull-out load. The anchorage depth and the region of contact with the adhesives or binder determine the failure mechanism of post-installed rebar connections. Due to the higher strength at the interface between the binder and the rebar in comparison to the binder-concrete, larger rebar diameters favour splitting or failure of concrete.