Polyethylene Glycol Concentration Research Articles

Primary, seminal and lateral roots of maize show type-specific growth and hydraulic responses to water deficit.

The water uptake capacity of a root system is determined by its architecture and hydraulic properties, which together shape the root hydraulic architecture. Here, we investigated root responses to water deficit (WD) in seedlings of a maize (Zea mays) hybrid line (B73H) grown in hydroponic conditions, taking into account the primary root (PR), the seminal roots (SR), and their respective lateral roots. WD was induced by various polyethylene glycol concentrations and resulted in dose-dependent inhibitions of axial and lateral root growth, lateral root formation, and hydraulic conductivity (Lpr), with slightly distinct sensitivities to WD between PR and SR. Inhibition of Lpr by WD showed a half-time of 5 to 6 min and was fully (SR) or partially (PR) reversible within 40 min. In the two root types, WD resulted in reduced aquaporin expression and activity, as monitored by mRNA abundance of 13 plasma membrane intrinsic protein (ZmPIP) isoforms and inhibition of Lpr by sodium azide, respectively. An enhanced suberization/lignification of the epi- and exodermis was observed under WD in axial roots and in lateral roots of the PR but not in those of SR. Inverse modeling revealed a steep increase in axial conductance in root tips of PR and SR grown under WD that may be due to the decreased growth rate of axial roots in these conditions. Overall, our work reveals that these root types show quantitative differences in their anatomical, architectural, and hydraulic responses to WD, in terms of sensitivity, amplitude and reversibility. This distinct functionalization may contribute to integrative acclimation responses of whole root systems to soil WD.

Tunable gas selectivity of cellulose nanocrystals – Polyethylene glycol composite membranes

The kinetics of the CO2, D2 and CH4 transport through self-supporting cellulose nanocrystals (CNCs) films containing low-molecular weight poly(ethylene glycol) (PEG) additive as plasticizer agent was studied in single gas condition at 293 K and sub-atmospheric feed pressure. Neat CNC and PEG-CNC with 7 wt % PEG films act as impermeable barrier for CO2 and CH4 and exhibit D2 permeability values not larger than 0.05 barrer with penetrant diffusivity in the 10−10 cm2/s range. PEG addition at larger contents improves the permeability and diffusivity of all penetrant gases and gives to the PEG-CNC membrane a CO2 selective character. The CO2 permeability and ideal CO2/D2 selectivity of the PEG-CNC films are 0.42 ± 0.04 barrer and ∼3, respectively, at 14 wt % PEG content, 2.5 ± 0.2 barrer and ∼5 at 21 wt % PEG. The preferred CO2 transport exhibits a solution-selective character being the D2 diffusivity a factor ∼10 larger than the CO2 diffusivity. PEG addition, on the contrary, does not change the D2 selective character for the D2/CH4 gas couple. PEG well mixed with the gas-impermeable CNCs increases the PEG-CNC free volume and preferentially improves the CO2 solubility given the specific interactions between the quadrupolar CO2 penetrant and the dipolar ether groups of the PEG additive.

Genome-Wide Identification and Expression Analysis of GATA Family Genes in Dimocarpus longan Lour.

GATA transcription factors, which are DNA-binding proteins with type IV zinc finger binding domains, have a role in transcriptional regulation in biological organisms. They have an indispensable role in the growth and development of plants, as well as in improvements in their ability to face various environmental stresses. To date, GATAs have been identified in many gene families, but the GATA gene in longan (Dimocarpus longan Lour) has not been studied in previous explorations. Various aspects of genes in the longan GATA family, including their identification and classification, the distribution of their positions on chromosomes, their exon/intron structures, a synteny analysis, their expression at different temperatures, concentration of PEG, early developmental stages of somatic embryos and their expression levels in different tissues, and concentrations of exogenous hormones, were investigated in this study. This study showed that the 22 DlGATAs could be divided into four subfamilies. There were 10 pairs of homologous GATA genes in the synteny analysis of DlGATA and AtGATA. Four segmental replication motifs and one pair of tandem duplication events were present among the DlGATA family members. The cis-acting elements located in promoter regions were also found to be enriched with light-responsive elements, which contained related hormone-responsive elements. In somatic embryos, DlGATA4 is upregulated for expression at the globular embryo (GE) stage. We also found that DlGATA expression was strongly up-regulated in roots and stems. The study demonstrated the expression of DlGATA under hormone (ABA and IAA) treatments in embryogenic callus of longan. Under ABA treatment, DlGATA4 was up-regulated and the other DlGATA genes did not respond significantly. Moreover, as demonstrated with qRT-PCR, the expression of DlGATA genes showed strong up-regulated expression levels under 100 μmol·L-1 concentration IAA treatment. This experiment further studied these and simulated their possible connections with a drought response mechanism, while correlating them with their expression under PEG treatment. Overall, this experiment explored the GATA genes and dug into their evolution, structure, function, and expression profile, thus providing more information for a more in-depth study of the characteristics of the GATA family of genes.

Countercurrent preferential precipitation of acidic variants from monoclonal antibody pools

The process of countercurrent multistage precipitation (CnMP) was developed for reduction of the acidic variant (av) content in monoclonal antibody (mAb) pools. The process was performed in polyethylene glycol (PEG) solutions of low ionic strength, at which av was the most prone to precipitate. To design the process, a mathematical model was formulated, which consisted of steady-state mass balance equations and underlying thermodynamic dependencies. The model was solved for different combinations of the process variables, including the protein concentration in the feed material and the PEG concentration in subsequent precipitation stages. The model solution was projected onto two-dimensional planes, where the performance indicators, such as the separation yield and the av reduction level, were correlated with the process variables. CnMP overperformed crosscurrent multistage precipitation (CsMP) and ion exchange chromatography (IEX) used in previous studies; in the comparison with CsMP, the 3-stage CnMP process allowed up to 28% increase in yield and up to 25% increase in the av reduction level, and in the comparison with IEX, up to 37% increase in yield and up 12.5% increase in the av reduction level. The yield benefit of CnMP depended on the composition of the feed material and the demand for the av reduction. The concept was experimentally verified; the 2- and 3-stage CnMP processes were performed using the input process variables provided by the model solution. The performance indicators calculated by the model and experimentally measured were in a good agreement, which indicated both feasibility and predictability of CnMP.

Using Carbonized Cotton Fabric Waste to Prepare Poly(ethylene glycol) Composite Phase Change Materials with Improved Thermal Conductivity and Solar-to-Thermal Conversion.

Poly(ethylene glycol) (PEG) boasts excellent thermal energy storage capabilities but lacks efficiency in thermal conductivity and solar absorption. Simultaneously, the escalating concern surrounding the substantial volume of discarded cotton fabric underscores environmental issues. In this study, we devised composite phase change materials (PCMs) by embedding PEG into a carbon cotton material (CCM), varying PEG content from 50 to 80%, and conducted a comprehensive analysis of their thermal properties and solar-to-thermal conversion. The CCM, crafted from a waste 100% cotton towel through carbonization, provided an optimal porous structure that accommodated a significant 70% PEG content without any leakage, thanks to interactions such as surface tension, capillary forces, and interfacial hydrogen bonds. These PEG/CCM composites exhibited impressive crystallization fractions (>92%), resulting in notable thermal energy storage capacities ranging from 85.3 to 143.2 J/g as the PEG content increased from 50 to 80%. Moreover, these composites showed high thermal stability and exceptional cycling durability even after 500 melting/crystallization cycles. Notably, their thermal conductivities markedly increased to a range of 0.46-0.85 W/m·K compared to pure PEG's modest 0.24 W/m·K. Furthermore, the PEG/CCM composites substantially augmented visible and near-infrared (VIS-NIR) light absorption. Evaluation of solar-to-thermal conversion illustrated the composite's ability to efficiently convert solar energy into thermal energy, storing and subsequently releasing it through melting and crystallization processes. This study introduces a novel class of composite PCMs characterized by cost-effectiveness, outstanding thermal performance, and impressive solar-to-thermal conversion capabilities. These composite PCMs hold significant promise for large-scale solar-to-thermal energy storage applications while contributing to the sustainability of cotton waste management.

Structure of polyethylene glycol/water mixtures as a separation medium of aqueous two-phase extraction systems studied by equilibrium analysis of thiocyanato complexation of Cobalt(II)

Aqueous two-phase systems (ATPS) utilizing polyethylene glycol (PEG) have been successfully used for the separation of various organic and inorganic compounds as an environmentally benign extraction method. However, a fundamental understanding of the role of the hydration structures around PEG chains in solute partitioning in ATPS remains elusive although it has been considered that PEG molecules are involved in separation. In the present work, the equilibria of Co(II) thiocyanate complexation reaction in aqueous PEG solutions were studied by spectrophotometry with varying ethylene oxide chain length and concentration of PEG. From the formation constants of the tetrahedral and octahedral Co(II) thiocyanate complexes obtained, a microheterogeneous structure consisting of pseudo phases formed by hydration of ethylene oxide (EO) chain and terminal hydroxyl (OH) groups in the PEG molecule in addition to the bulk water phase was estimated. It was revealed that the formation of tetrahedral Co(NCS)42− complex proceeds in the EO pseudo phase by the involvement of hydrophobic ethylene groups, while the OH phase and the bulk phase inhibit the progress of the reaction. This indicates that Co(NCS)42− is stable in hydrophobic hydration structure of water around the EO moiety. The EO phase imparts hydrophobicity to aqueous PEG solutions and plays a predominant role in partition of solute molecules in PEG-based ATPS.

Preparation and characterization of amphiphilic, biodegradable, waterborne polyurethanes without using organic solvent and catalyst.

Traditionally, waterborne polyurethanes (WPUs) are prepared using toxic organic solvents and catalysts. These WPUs are non-biodegradable and are buried or incinerated after the expiration date. This has adverse effects on the environment and human health, which limits the applications of WPUs. Herein, a special synthetic method was developed for biodegradable waterborne polyurethane (BWPU) by adding hydrophilic prepolymers into WPU prepolymers without using organic solvents and catalysts. Different proportions of polyethylene glycol (PEG) were introduced into polycaprolactone (PCL)-based BWPUs to improve the comprehensive properties. Results showed that as the PEG content was increased from 0 to 16 wt%, the solid content of BWPU increased from 34.8 wt% to 53.1 wt%, while the tensile strength and Young's modulus of BWPU films increased from 21.81 MPa to 56.83 MPa and 8.08 MPa to 19.4 MPa, respectively. However, the elongation at break did not decrease significantly, but still reached 827.17%. With an increase in PEG content, the crystallinity and phase separation decreased, while the hydrophilicity and surface energy increased for BWPU films. In addition, the prepared BWPUs had good biodegradability in PBS/lipase solution. The mass loss of BWPU without PEG reached 6.3 wt% after 4 weeks of degradation, whereas the mass losses of BWPUs with PEG reached 2.3-4.3 wt%. Obviously, the introduction of PEG did not increase biodegradability. Thus, the higher the PCL content, the faster the biodegradation rate. This work would provide an effective method for the preparation of ecofriendly biodegradable BWPU with excellent comprehensive properties.

The effects of plasticizers on the mechanical properties and chemical composition of a gelatin biopolymer

Every day, oil-based plastics are manufactured, consumed, and discarded without a second thought. To combat plastic pollution, we decided to investigate gelatin bioplastics. We analysed the effects of the increasing concentration of polyethylene glycol (PEG) and glycerol plasticizers on the mechanical properties and chemical composition of the gelatin bioplastic matrix through a series of experiments. In the first experiment, we determined their tensile strength (TS) and the elongation at break (EAB) through tensile testing. We hypothesised that increasing concentrations of the plasticizers would decrease TS and increase EAB. In the second experiment, we studied their O–H bonds by Fourier-transform infrared spectroscopy analysis (FTIR). Our second hypothesis maintained that the number of O–H bonds would increase because plasticizers disrupt polymer-polymer and polymer-water hydrogen bonds. For the mechanical properties, we observed that when the concentration of PEG and glycerol plasticizers increased so too did EAB. The rising concentrations of glycerol led to a decreasing trend with TS, whereas PEG showed an increasing trend. The FTIR spectrum revealed that a high abundance of O–H bonds was present at the strong and broad absorption peak of 3400 cm-1, with the pure gelatin films having the highest absorption, followed by glycerol-plasticized films and PEG-plasticized films having the least absorption. We concluded that 3% w/v PEG film outperformed other PEG films and 3% w/v glycerol films. The cytotoxicity results showed that all films had a cell viability above the threshold of 75% and hence food-safe.

Intracellular trafficking kinetics of nucleic acid escape from lipid nanoparticles via fluorescence imaging.

Lipid nanoparticles (LNPs) are one of the most clinically advanced candidates for delivering nucleic acids to target cell populations, such as hepatocytes. Once LNPs are endocytosed, they must release their nucleic acid cargo into the cell cytoplasm. For delivering messenger RNA (mRNA), delivery into the cytosol is sufficient; however, for delivering DNA, there is an added diffusional barrier needed to facilitate nuclear uptake for transcription and therapeutic effect. Here, we use fluorescence microscopy to investigate the intracellular fate of different LNP formulations to determine the kinetics of localization to endosomes and lysosomes. LNPs used in the studies were prepared via self-assembly using a NanoAssemblr for microfluidic mixing. As the content of polyethylene glycol (PEG) within the LNP formulation influences cellular uptake by hepatocyte cells, the content and hydrocarbon chain length within the formulation were assessed for their impact on intracellular trafficking. Standard LNPs were then formed using three commercially available ionizable lipids, Dlin-MC3-DMA (MC3), Dlin-KC2-DMA (KC2), and SS-OP. Plasmid DNA (pDNA) and mRNA were used, more specifically with a mixture of Cyanine 3 (Cy3)-labeled and green fluorescence protein (GFP) producing plasmid DNA (pDNA) as well as Cy5-labeled GFP producing mRNA. After formulation, LNPs were characterized for the encapsulation efficiency of the nucleic acid, hydrodynamic diameter, polydispersity, and zeta potential. All standard LNPs were ~100 nm in diameter and had neutral surface charge. All LNPs resulted in encapsulation efficiency greater than 70%. Confocal fluorescence microscopy was used for the intracellular trafficking studies, where LNPs were incubated with HuH-7 hepatocyte cells at times ranging from 0-48 h. The cells were antibody-stained for subcellular components, including nuclei, endosomes, and lysosomes. Analysis was performed to quantify localization of pDNA to the endosomes and lysosomes. LNPs with 1.5 mol% PEG and a hydrocarbon chain C14 resulted in optimal endosomal escape and GFP production. Results from this study demonstrate that a higher percentage of C14 PEG leads to smaller LNPs with limited available phospholipid binding area for ApoE, resulting in decreased cellular uptake. We observed differences in the localization kinetics depending on the LNP formulation type for SS-OP, KC2, and MC3 ionizable lipids. The results also demonstrate the technique across different nucleic acid types, where mRNA resulted in more rapid and uniform GFP production compared to pDNA delivery. Here, we demonstrated the ability to track uptake and the sub-cellular fate of LNPs containing pDNA and mRNA, enabling improved screening prior to in vivo studies which would aid in formulation optimization.

Exogenous Ca/Mg quotient reduces the inhibitory effects of PEG induced osmotic stress on Avena sativa L.

Drought is one of the most damaging abiotic stress that hinder plant growth and development. The present study aimed to determine the effects of various Ca/Mg quotients under polyethylene glycol (PEG)-induced osmotic stress on growth, uptake and translocation of Ca and Mg in Avena sativa (L). Plants were grown in nutrient solution supplemented with three different Ca/Mg molar quotients (0.18, 2, and 4). After 30 days plants were exposed to two different PEG (Polyethylene glycol) concentrations (0.6 MPa & 0.2 MPa) for 8 days, and solutions were renewed after 4 days. A solution containing Ca and Mg nutrients has mitigated the negative impact caused via osmotic stress on relative growth rate (RGR), absolute growth rate (AGR), crop growth rate (CGR), leaf area ratio (LAR), Leaf index ratio (LAI), root-shoot ratio (RSR), water use efficiency (WUE) and net assimilation rate (NAR). In addition, it adversely affected germination parameters, including final emergence percentage (FEP), mean germination time (MGT), Timson germination Index (TGI), germination rate index (GRI) and percent field capacity (%FC), of oat (Avena sativa L.). Mg and Ca in shoot and root and Ca translocation factor decreased with increasing Ca in solution, while Mg translocation factor increased with increasing Ca in nutrient solution. In this work, the combined effects of various Ca/Mg quotients and osmotic stress produced by polyethylene glycol (PEG) in different concentrations (0.6 MPa, 0.2 MPa) on the growth and element uptake of Avena sativa L. are examined. As a result, the Ca/Mg Quotient may naturally combat the moderate drought stress experienced by field crops.

Penicillium citrinum CFAM 521 Isolated From the Amazon Region: A Novel Source of a Fibrinolytic Enzyme.

Fibrinolytic agents are essential in treating thrombosis, playing a critical role in improving survival rates in cardiovascular diseases. Microbial fibrinolytic proteases have emerged as promising alternatives due to their affordability, specificity, lower toxicity, and reduced side effects. Consequently, the search for microorganisms capable of producing these enzymes has gained significant economic importance in the pharmaceutical industry. This study reports and characterizes a novel fibrinolytic enzyme produced by Penicillium citrinum CFAM 521, a strain isolated from the Amazon region. The enzyme was purified using a polyethylene glycol (PEG)-phosphate salt aqueous two-phase system (ATPS). The effects of PEG molecular weight, PEG concentration, and phosphate concentration on the protease partition coefficient (K) were evaluated through a 22 full factorial design. The enzyme exhibited both fibrinolytic and fibrinogenolytic activities. After partitioning in a two-phase system with 10% (w/w) PEG and 15% (w/w) sodium phosphate, the fibrinolytic proteases were predominantly retained in the salt-rich bottom phase (K = 0.33). The enzyme has a molecular weight of 34 kDa, with optimal pH and temperature at 9°C and 37°C, respectively. Inhibitory analysis confirmed that it is a serine protease, and its activity was enhanced by the addition of Mn2+. Notably, the enzyme exhibited no hemolytic activity. Therefore, P. citrinum CFAM 521 represents a novel source of fibrinolytic enzymes, highlighting its potential as an alternative for the development of thrombolytic agents.

Tuning the water intrinsic permeability of PEGDA hydrogel membranes by adding free PEG chains of varying molar masses.

We explore the effect of poly(ethylene glycol) (PEG) molar mass on the intrinsic permeability and structural characteristics of poly(ethylene glycol) diacrylate PEGDA/PEG composite hydrogel membranes. We observe that by varying the PEG content and molar mass, we can finely adjust the water intrinsic permeability by several orders of magnitude. Notably, we show the existence of maximum water intrinsic permeability, already identified in a previous study to be located at the critical overlap concentration C* of PEG chains, for the highest PEG molar mass studied. Furthermore, we note that the maximum intrinsic permeability follows a non-monotonic evolution with respect to the PEG molar mass and reaches its peak at 35 000 g mol-1. Besides, our results show that a significant fraction of PEG chains is irreversibly trapped within the PEGDA matrix even for the lowest molar masses down to 600 g mol-1. This observation suggests the possibility of covalent grafting of the PEG chains onto the PEGDA matrix. CryoSEM and AFM measurements demonstrate the presence of large micron-sized cavities separated by PEGDA-rich walls whose nanometric structures strongly depend on the PEG content. By combining our permeability and structural measurements, we suggest that the PEG chains trapped inside the PEGDA-rich walls induce nanoscale defects in the crosslinking density, resulting in increased permeability below C*. Conversely, above C*, we speculate that partially trapped PEG chains may form a brush-like arrangement on the surface of the PEGDA-rich walls, leading to a reduction in permeability. These two opposing effects are anticipated to exhibit molar-mass-dependent trends, contributing to the non-monotonic variation of the maximum intrinsic permeability at C*. Overall, our results demonstrate the potential to fine-tune the properties of hydrogel membranes, offering new opportunities for separation applications.

Preparation of PEG/P(U-AM-ChCl) composite hydrogels using ternary DES light polymerization and their properties.

Deep eutectic solvents (DES) were prepared using urea (U) and acrylamide (AM) as hydrogen bond donors (HBD) and choline chloride (ChCl) as hydrogen bond acceptor (HBA), and polyethylene glycol (PEG) was selected as a filler and uniformly dispersed in DES to prepare PEG/P(U-AM-ChCl) composite hydrogels by light polymerization. The composite hydrogels were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The effects of the content of PEG on the swelling properties, mechanical properties and fatigue resistance of the composite hydrogels were investigated. The results showed that the compressive strength and fatigue strength of the composite hydrogels were gradually enhanced with the increase of the PEG content in the composite hydrogels, in which the maximum compressive strength of the hydrogels with 1 wt% PEG added was increased by 1.86 times. The composite hydrogel had excellent swelling properties, and the equilibrium swelling degree of the hydrogel with 1 wt% PEG added reached 10.15. Meanwhile, the PEG/P(U-AM-ChCl) composite hydrogel had excellent self-healing properties, and the self-healing rate of the composite hydrogel with a PFG content of 1 wt% could reach 91.93% after 48 hours of healing. This study provides a convenient and efficient method to prepare composite hydrogels with superior swelling properties and self-healing properties.

Polyethylene glycol-decorated n-type conducting polymers with improved ion accessibility for high-performance organic electrochemical transistors.

High-performance n-type organic mixed ionic-electronic conductors (OMIECs) are essential for advancing complementary circuits based on organic electrochemical transistors (OECTs). Despite significant progress, current n-type OMIECs often exhibit lower transconductance and slower response times compared to their p-type counterparts, limiting the development of OECT-based complementary circuits. Optimizing the conjugated backbone and side chain structures of OMIECs is critical for enhancing both ion and electron transport efficiencies while maintaining a delicate balance between the two. In this study, hydrophilic polyethylene glycol (PEG) side chains were incorporated into the highly conductive n-type polymer poly(3,7-dihydrobenzo[1,2-b:4,5-b']difuran-2,6-dione) (PBFDO) backbone to achieve this goal. The incorporation of PEG chains improved ion accessibility, and by adjusting the PEG content, the electronic and ionic transport properties were fine-tuned, ultimately enhancing the performance of OECTs and related p-n complementary circuits. The n-type OECTs based on PBFDO-PEG50wt% demonstrated exceptional transfer characteristics, including a transient response time (τON) as low as 72 μs, a high geometry-normalized transconductance exceeding 400 S cm-1, and an impressive μC* value surpassing 720 F cm-1 V-1 s-1. Notably, the use of PBFDO-PEG50wt% in a complementary inverter resulted in a voltage gain of 20 V/V, more than five times higher than that achieved with unmodified PBFDO (<4 V/V). These findings highlight the importance of balancing electron and ion transport characteristics in OMIECs to achieve high performance in OECTs and their associated circuits, and they validate PEG decoration as an effective approach.

Enhancement of covalent triazine frameworks containing S heteroatom for photocatalytic hydrogen evolution: the role of composite PEG

The higher the content of PEG filled in the pores of TTBT-COF, the higher the hydrogen evolution rate. The photocatalytic hydrogen evolution rate of TTBT-COF@PEG30 is 1.51 times that of pristine TTBT-COF.

Influence of PEG content on optical band gap and laser damage characteristics of porous films

Influence of PEG content on optical band gap and laser damage characteristics of porous films

Impact of water stress on morpho-physiological and biochemical traits in rice genotypes

Laboratory and field screening were performed in nine rice genotypes i.e., TM 12061, TM 12077, TM 12012, TM 14035, TM 16017, Senthuram, Vandhana, TKM 12 and Anna (R) 4 to assess their drought tolerant potential. For laboratory screening, the effect of different levels of Poly Ethylene Glycol (PEG) concentration viz., -0.2, -0.4, -0.6 and -1.0 MPa on germination, shoot length and root length were studied. There was a considerable decrease in the germination potential among all the genotypes with increase in PEG concentration. The TM 12077 showed higher level of tolerance to PEG induced drought stress showing 30.8 % germination with 3.2 cm and 8.85 cm shoot and root length, respectively at higher level of concentration (1.0 MPa). In the field screening under managed stress condition, TM 12077 and TM 12012 showed higher accumulation of proline (4.15 mg/g). Chlorophyll stability index was more than 80 % in the genotypes TM 12012, TM 12077 and TM 12061. The genotype TM 14035, the varieties Anna (R) 4 and Vandhana matured early in 115 days. Number of tillers per plant, number of panicles/sqm and yield/hectare were maximum in TM 12077. While considering both laboratory and field screening, the genotypes TM 12077, TM 12012 and TM 12061 were found promising for water stress environment and can be utilized as donors in the drought tolerance breeding programs. High heritability coupled with moderate to high GA as per cent of mean recorded for plant height, tillers per plant, chlorophyll stability Index and total chlorophyll content indicates the presence of additive gene effects and their improvement through direct selection. Bangladesh J. Bot. 52(4): 1041-1046, 2023 (December)

İki Amerikan Asma Anacının Kuraklık Stresine Toleransının PEG Uygulaması ile Belirlenmesi

Objective: This study was conducted to establish the in vivo protocol for the use of polyethylene glycol (PEG-6000) in 5BB (V. berlandieri x V. riparia) and 1103P (V. berlandieri x V. rupestris) American grapevine rootstocks, as well as to determine the plants' resilience to artificially induced drought stress.&#x0D; Materials and Methods: The experimental design of this study was planned as a randomized complete plot design with 3 replications, each consisting of 10 plants. Polyethylene glycol (PEG-6000) was administered to the plants in each irrigation at doses of 0%, 2%, 4%, 8%, and 16%, based on the percentage of irrigation water. The application lasted for a total of 3 weeks. The study investigated the responses of plants to drought in terms of shoot development parameters (shoot fresh weight, shoot dry weight, shoot length, node and leaf number, leaf area, shoot tolerance ratio), root development parameters (root fresh weight, root number, rooting rate, root tolerance ratio, root length), and physiological development parameters (plant vitality, damage degree, leaf turgor weight, chlorophyll content, ion flux, and cell membrane damage rate).&#x0D; Results: When examining the findings of the study, it was observed that polyethylene glycol material retained water, reducing the plant's water uptake and consequently creating artificial drought stress. The impact of drought induced by polyethylene glycol revealed that the 1103P rootstock exhibited higher resilience in shoot development parameters compared to the 5BB rootstock. On the contrary, the 5BB rootstock outperformed the 1103P rootstock in root development parameters. Concerning physiological development parameters, the severity of drought led to a significant decrease in plant vitality, chlorophyll content, and leaf turgor weight, while ion flux, cell membrane damage rate, and damage degree increased significantly to critical levels.&#x0D; Conclusion: As a result of the research, the 1103P rootstock was found to be more successful in terms of shoot and physiological development under drought conditions, while the 5BB rootstock was found to be more successful in terms of root development parameters. Compared to other cultivation environments (in vitro, hydroponics), it was determined that polyethylene glycol (PEG) had a less pronounced effect at lower doses due to the difficulty of binding PEG in the soil. However, when compared to control plants, statistically significant differences were observed in the examined traits. Regarding the parameters investigated in this study, the 16% PEG concentration used was identified as the most effective dose in triggering drought stress.

Physiological Insights of Melatonin Hormone for Alleviation of Drought Stress in Rice

Drought stress significantly hampers crop growth and yield by negatively impacting various biochemical and physiological plant processes. This study aimed to assess drought tolerance in traditional rice varieties using Poly Ethylene Glycol 6000 (PEG 6000) and focused on the effectiveness of melatonin applied through both seed treatment and foliar spray in mitigating the effects of drought stress. The optimal drought screening conditions were determined at a PEG concentration of -4 bars. As the PEG concentration increased, key factors such as germination percentage, vigor index, root length, and shoot length decreased. This indicates that PEG can be a useful tool for early selection of drought tolerant rice varieties. Melatonin (N-acetyl-5-methoxytryptamine), known for alleviating abiotic stress, showed positive effects on seed germination at 200 ppm concentration. The study observed that stomatal closure is a natural response to drought stress, but melatonin application induced partial stomatal opening. Notably, a foliar spray of 100 ppm melatonin demonstrated better recovery from drought stress compared to the 200 ppm concentration. In conclusion, the research suggests that seed treatment with 200 ppm melatonin and foliar spraying with 100 ppm melatonin are the most effective approaches for reducing the adverse effects of drought stress in rice plants.

Recyclable polytriazole resins with high performance based on Diels-Alder dynamic covalent crosslinking

Abstract N,N-Di-2-propyn-1-yl-2-furanmethanamine (DPFA) was synthesized from 2-furanemethylamine and 3-chloropropyne. Then, furan-containing polytriazoles were made from DPFA and diazide compounds. The Diels-Alder (DA) reaction between 4,4′-bismaleimidodiphenylmethane and furan-containing polytriazoles was used to prepare recyclable polytriazole resins. The effects of the main chain structures on the reversible processes and mechanical properties of the resins were investigated. The results show that the flexibility of the chain structures could be regulated by introducing different contents of azide-terminated polyethylene glycol (PEG) in the polymerization process. The PEG segments could not only promote the degree of the DA reaction but also play a role in reinforcing and/or toughening the recyclable polytriazole resins. RFPTA-5 resin film displays a tensile strength of 107.2 MPa and RFPTA-20 resin film shows an elongation at break of 224.8%. Moreover, the resin films demonstrate high recyclability.