Carbamate Group Research Articles

High Leach-Resistant Fire-Retardant Modified Pine Wood (Pinus sylvestris L.) by In Situ Phosphorylation and Carbamylation.

The exterior application of fire-retardant (FR) timber necessitates it to have high durability because of the possibility to be exposed to rainfall. In this study, water-leaching resistance of FR wood has been imparted by grafting phosphate and carbamate groups of the water-soluble FR additives ammonium dihydrogen phosphate (ADP)/urea onto the hydroxyl groups of wood polymers via vacuum-pressure impregnation, followed by drying/heating in hot air. A darker and more reddish wood surface was observed after the modification. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, solid-state 13C cross-polarization magic-angle-spinning nuclear magnetic resonance (13C CP-MAS NMR), and direct-excitation 31P MAS NMR suggested the formation of C-O-P covalent bonds and urethane chemical bridges. Scanning electron microscopy/energy-dispersive X-ray spectrometry suggested the diffusion of ADP/urea into the cell wall. The gas evolution analyzed by thermogravimetric analysis coupled with quadrupole mass spectrometry revealed a potential grafting reaction mechanism starting with the thermal decomposition of urea. Thermal behavior showed that the FR-modified wood lowered the main decomposition temperature and promoted the formation of char residues at elevated temperatures. The FR activity was preserved even after an extensive water-leaching test, confirmed by the limiting oxygen index (LOI) and cone calorimetry. The reduction of fire hazards was achieved through the increase of the LOI to above 80%, reduction of 30% of the peak heat release rate (pHRR2), reduction of smoke production, and a longer ignition time. The modulus of elasticity of FR-modified wood increased by 40% without significantly decreasing the modulus of rupture.

Bio-Based Poly(hydroxy urethane)s for Efficient Organic High-Power Energy Storage

Fast, low-cost, and efficient energy storage technologies are urgently needed to balance the intermittence of sustainable energy sources. High-power capacitors using organic polymers offer a green and scalable answer. They require dielectrics with high permittivity (εr) and breakdown strength (EB), which bio-based poly(hydroxy urethane)s (PHUs) can provide. PHUs combine high concentrations of hydroxyl and carbamate groups, thus enhancing their εr, and a highly tunable glass transition (Tg), which dictates the regions of low dielectric losses. By reacting erythritol dicarbonate with bio-based diamines, fully bio-based PHUs were synthesized with Tg ∼ 50 °C, εr > 8, EB > 400 MV·m-1, and low losses (tan δ < 0.03). This results in energy storage performance comparable with the flagship petrochemical materials (discharge energy density, Ue > 6 J·cm-3) combined with a remarkably high discharge efficiency, with η = 85% at EB and up to 91% at 0.5 EB. These bio-based PHUs thus represent a highly promising route to green and sustainable energy storage.

Microstructure construction design and damping properties of polyurethane microporous elastomer modified by suspension chain extender via end-controlling oriented synthesis

Broadening the damping temperature range of viscoelastic microporous polyurethane elastomers (MPUE) is a challenge to break the limits of practical applications in damping field. Based on the molecular reaction kinetics and the molecular structure design of MPUE, different molecular weight suspension chain extenders were synthesized from polyethylene glycol monomethyl ether (MPEG), isophorone diisocyanate (IPDI) and 2-amino-1,3-propanediol via end-controlling oriented synthesis. The effect of molecular weight and dosages of suspension chain extenders on the damping property of MPUE was studied. It was demonstrated that strong intermolecular hydrogen bonds can be formed between MPUE molecules due to the carbamate groups and urea groups of the suspension chain extenders. The transformations of various motion modes of the suspended chain were driven by the existence of a large number of ether bonds, which can reduce the micro-phase separation degree in the material matrix, resulting in higher kinetic friction between molecular chains. The damping properties of the material were significantly improved, presenting a maximum increase of 62.3% in the effective damping temperature domain, and a maximum increase of 34.0% in the peak loss factor (tan δ), which was attributed to the synergistic compound effect of multiple motion modes. This high damping MPUE has great application prospects in the fields of acoustic noise reduction and household appliances damping.

Cyclic carbamates in medicine: A clinical perspective.

Carbamate group is mainly used for designing prodrugs to achieve first-pass and systemic stability against enzyme hydrolysis as the carbamate functionality is recognized by esterase enzymes. As compared to the ester functionality, the carbamate group shows a lesser lability towards enzyme hydrolysis, but a higher susceptibility than amides. Cyclic carbamates present a unique motif in the contemporary drug discovery and development owing to the presence of a polar, and sterically small, constrained Hydrogen-bonding acceptor atom. The metabolic stability of 5/6-membered cyclic carbamates are higher as compared to their acyclic counterparts as the former do not undergo metabolic ring opening under physiological conditions. Besides, the metabolic lability of acyclic carbamates is determined by the degree of substitution at the endocyclic/exocyclic "N" atom, which further enables the design and development of various carbamate drugs or prodrugs. As such, the metabolic stability of carbamates follows the order: Cyclic carbamates > Alkyl-OCO-NH2 » Alkyl-OCO-NHAcyl ∼ Alkyl-OCO-NHAryl ≥ Aryl-OCO-N(endocyclic) ∼ Aryl-OCO-N(Alkyl)2 ≥ Alkyl-OCO-N(endocyclic) ≥ Alkyl-OCO-N(Alkyl)2 ∼ Alkyl-OCO-NHAlkyl » Aryl-OCO-NHAlkyl.

P-Terphenyl-based rigid stationary phases with embedded polar groups for liquid chromatography

Terphenyls are important building blocks for a wide range of functional molecules. Among the three isomers, p-terphenyl (C18H14) is particularly useful for the construction of optical devices on account of its unique structure. Herein, two rigid stationary phases bearing p-terphenyl as an external moiety and variable embedded carbamate groups (p-TerC with one embedded carbamate group and p-TerC2 with two embedded carbamate group) were presented. The proposed stationary phases were characterized by various means and evaluated in reversed-phase (RP) mode, using different classes of analytes, including polycyclic aromatic hydrocarbons (PAHs), alkylbenzenes, 4-alkylbiphenyls, substituted ureas, sulfonylureas, substituted sulfanilamides and aromatic acids. The comparison with conventional C18, several other polar-embedded aromatic and C18 equivalents indicated p-terphenyl-based stationary phases were featured by multiple retention mechanisms, involving π-π interaction, charge-transfer interaction, hydrogen-bonding and hydrophobic interaction in RP mode. A unusually high specificity to the analytes with linear structures was observed, as exemplified by an irreversible adsorption of tetracene and a readily separation of tetraphene and chrysene. The aliphatic linker used in the proposed stationary phases was an influential factor for retentivity, selectivity and column efficiency. Interestingly, p-TerC2 was operable in normal-phase mode for the separation of certain PAHs through polar-related interactions. The linear, rigid polyphenyl structure of p-terphenyl endowed the new stationary phase with distinctive chromatographic properties, in contrast to those of the preceding counterparts bonded with alkyl and/or polynuclear aromatic moieties.

Waterborne polyurethane acrylate emulsion with dangling chain structure: Simultaneously showing wide damping temperature range and excellent hydrophobic performance

AbstractWaterborne polyurethane (WPU) damping material has been drawing much attention in academic field because of its low toxicity compared with polyurethane (PU) damping material. In order to expand the application range of WPU damping materials, it is necessary to further improve the hydrophobicity and damping properties of WPU. A novel dangling chain polyol‐n (DCP‐n, n expressed as average molecular weight of MPEG) was synthesized from methoxypolyethylene glycol (MPEG), isophorone diisocyanate (IPDI) and 1,1,1‐tris (hydroxymethyl) propane (TMP). Subsequently, a series of dangling chain‐n‐waterborne polyurethane acrylate (DC‐n‐WPUA, n expressed as average molecular weight of MPEG) emulsions were synthesized using DCP‐n as the chain extender. The increase of DCP‐n length will fill in free volume, hinder the entry of water molecules. Therefore, improve the hydrophobic performance. In addition, the increase of DCP‐n length will lead to more intermolecular friction, which can increase the dissipation of energy, and improves the damping performance of DC‐n‐WPUA. The test results show that the hydrophobicity of DC‐n‐WPUA film is improved, and the maximum static water contact angle can reach 110.6°. Dynamic mechanical analysis testing data showed that DC‐500‐WPUA has the best damping performance, and its effective damping temperature range was 77.9°C (−32.0 ~ 45.9°C). The carbamate group on DCP‐n will produce hydrogen bonds to restrict the movement of the chain segments, and the hydrogen bond breakage requires more energy. This ameliorates the thermal stability and mechanical properties of DC‐n‐WPUA. Thus, the initial modulus of DC‐n‐WPUA larger than the initial modulus of WPUA. Therefore, the DC‐n‐WPUA have the potential to be applied to hydrophobic damping coatings in the future.

The Bio-efficacy of Inesfly vesta 50 (Transfluthrin 0.5% w/w) insecticidal paint: An alternative vector control intervention against Anoheples gambiae mosquitoes under laboratory condition, Keffi, Nigeria

Malaria remains a major public health concern. Particularly in Nigeria where more than 80% of the cases are reported and locally among natives in Nigeria. There are serious indication of insecticide resistance in Nigeria. Under PMI/Vectorlink laboratory condition, cement plaster surface and wooden board were brushed with a primer within 24-48hours before the paint application. The inesfly vesta 50 (transfluthrin 0.5% w/w) insecticide paint was applied at the dosage of 8m2/L for cement and wooden board drying at room temperature for 5 days. The plastic cones were fixed on the treated walls and wooden board at 0.5m, 1.0m, and 1.5m parameters height, after which 10 non-blood fed females mosquito were gently introduced into the cone chamber for 30- 60 minutes observation. The holding paper cups were kept under favourable temperature of 27oc and humidity at 70%. In a dose trial finding, the data obtained were analyzed in IBM SPSS version 23.0 using ANOVA and the results presented as mean ± standard deviations of triplicate observations showed 100% yield (100.0±0.00*) mortality of malaria vector of novel trial with 0.5% w/w transfluthrin painted substrates in 24hours post exposure to 6months post application, except that, at l.5m in the month of July, 98% knockdown/mortality was recorded which follow same sequence of method and procedure in the application on the substrate absorbency, though, results showed high level of susceptibility from February to July (100% mortality rate). Results from wall cone and wooden board bio-assay residuality was alarming, with very high kill rates observed after 24hours post exposure. From the treated bio-assay of inesfly vesta 50 (Transfluthrin 0.5% w/w) by possible means showed that, this formulation is effective on malaria vector and possibly other insects. This suggests that, the transfluthrin 0.5% w/w can be tried alongside other known application with organophosphate, pyrethroids and the carbamate group, and can reduce human mosquito contact and impact on the perennial malaria transmission.

Design, Synthesis, and Insecticidal Evaluation of New Benzoylureas Containing Carbamate Groups Based on the Bipartite Model of Sulfonylurea Receptor Binding Site

Background: Benzoylureas are the most commonly used chitin synthesis inhibitors. But, the exact target site of benzoylurea insecticides has not been identified. Objective: To study whether benzoylphenylureas analogues with a bipartite model could be designed and synthesized as novel insecticides with improved activities. Methods: Based on the bipartite model of the sulfonylurea receptor binding site and commercial diflubenzuron, a series of novel benzoylureas containing carbamate groups were designed and synthesized via the key intermediate 2,6-difluoro-N-((4-hydroxyphenyl)carbamoyl)benzamide (2). The structures of the target compounds were confirmed by the 1H NMR and high-resolution mass spectrum (HRMS). Results: The results of bioassays indicated that these target compounds possessed good larvicidal activities against a broad spectrum of insects such as oriental armyworm (Mythimna Separata Walker), diamondback moth (Plutella xylostella), and mosquito (Culex pipiens pallens). A compound containing N, N-diisopropyl (3g) exhibited the highest insecticidal activity against oriental armyworm (40% at 10 mg kg-1), which was comparable with that of diflubenzuron. These compounds also had good larvicidal activities against diamondback moth and mosquito; most of these target compounds exhibited comparable larvicidal activities of diamondback moth with diflubenzuron and higher larvicidal activities of mosquito than diflubenzuron. Conclusion: The experimental data above preliminarily proved the rationality of our speculation and design ideology, and BPUs analogues with a bipartite model could improve the interaction with the target.

Influence of carbofuran on the concentration of primary soil macronutrients in potato growing areas in the Peruvian highlands

Potatoes have a high production demand in the world, but they are constantly under threat from germination to harvest due to pest infestation; for control, insecticides are used, which are highly polluting chemicals, systemic insecticides of the carbamate group due to their mode of action, with contact activity against different pests. This research sought to evaluate the influence of carbofuran on soil macronutrients in the District of Chongos Bajo, in the highlands of Peru. Through the experimental study method, with a quantitative research approach in a deductive process. We worked with a representative area of 10 m2 with 6 analyses of soil samples every 15 days in a period of 3 months. The results showed a loss value of 7.85% of total nitrogen, 14.05% of available phosphorus and 10% of available potassium in the period of 90 days, where there was a variation in the pH in water with a tendency of acidity, and a decrease in organic matter with a loss value of 6.93%. It was possible to demonstrate that the toxicity of the insecticide carbofuran had an influence on the decrease in the concentration of the main macronutrients and on the physical and chemical properties of the soil.

Assessment of developed paper strip based sensor with pesticide residues in different dairy environmental samples

According to the results of this study, the paper strip biosensor can detect pesticide at very low concentration like fungicide, organochlorine, organophosphate, carbamate, and herbicide group ranges from 1 to 10, 1–50, 250–500, 1–50, and 1 μg/L, respectively in animal feed, water, milk and soil. This is a significant improvement from the previous study, which found that the paper strip biosensor could only detect pesticide levels of up to 500 or 1000 μg/L. A total of 436 samples were collected from the dairy farm, including 58 samples of green feed, 54 samples of dry feed, 45 samples of concentrated feed, 41 samples of fermented feed, 49 samples of manure, 54 samples of soil, and 86 samples of milk. PSA (Primary Secondary Amine) and MgSO4 (1:2 ratio) were used to remove pigments from dairy farm samples to prevent the enzyme–pesticide interaction leading to colour development on the strip, which was successfully achieved. Using a strip-based test and an optimized extraction protocol, pesticides were detected in 38.49% in the samples. Limit of Detection of 15 pesticides from the organochlorine, organophosphate, carbamate, neonicotinoid, pyrethroid, ryanoid, strobilurins, and triazole groups recommended for use in dairy farms were evaluated in feed/fodder. Pesticides were being detected in various dairy farm matrices using the newly developed test. The developed technology can be used as a semi-quantitative test for pesticides monitoring in the dairy farm as well as for screening of primary produce under field condition for organic certification of various food/feed commodities.

The nicotinamide ruthenium(II) complex induces the production of reactive oxygen species (ROS), cell cycle arrest, and apoptosis in melanoma cells

A set of new ruthenium complexes, [RuCl(NIC)(dppb)(4,4′-Me-bipy)]PF6 (C1), [RuCl(NIC)(dppb)(4,4′-Methoxy-bipy)]PF6 (C2), and [RuCl(NIC)(dppb)(5,5′-Me-bipy)]PF6 (C3), where NIC = 3-pyridinecarboxamide, 4,4′-Me-bipy = 4,4′-dimethyl-2,2′-bipyridine, 4,4′-Methoxy-bipy = 4,4′-dimethoxy-2,2′-bipyridine, and 5,5′-Me-bipy = 5,5′-dimethyl-2,2′-bipyridine were synthesized and characterized by elemental analysis, UV/Vis and infrared spectroscopy, 31P{1H},1H, 13C{1H} nuclear magnetic resonance (NMR), and cyclic voltammetry. In addition, the structure of [RuCl(NIC)(dppb)(4,4′-Me-bipy)]PF6 was confirmed by single crystal X-ray diffraction (XRD). The solution stability study of C1-C3 showed the formation of pyridine which was coordinated due to solvent protic attacked to nicotinamide, and an elimination reaction of a carbamate group was observed. C1-C3 interacted with DNA through intercalation, electrostatic forces of attraction, or hydrogen bonding. The complexes interacted, moderately and spontaneously, with HSA, mainly through Van der Waals and hydrogen bond interactions. An in vitro evaluation of the (C1-C3) complexes revealed a cytotoxicity against MCF-7, HepG2, A549, SK-MEL-147, WM1366, and CHL-1. A higher cytotoxicity was observed for compound (C3) against melanoma cell cancer (CHL-1). Moreover, the (C3) complex inhibited the clonogenic capacity and cell cycle progression of CHL-1 cells and induced apoptosis involving the production of reactive oxygen species (ROS). [RuCl(py)(dppb)(5,5′-Me-bipy)]PF6 presented a very close C3 cytotoxicity against melanoma cell cancer (CHL-1).

Discovery of carbamate-based salicylic acid derivatives as novel cholinesterase inhibitor

Cholinesterase inhibition is a clinically validated therapeutic approach for treatment of Alzheimer's disease (AD). A series of salicylic acid-based ChE inhibitors bearing carbamate group were designed and synthesized based on the principle of active substructure splicing. Among them, compounds 3l (IC50, eqBChE = 1.06 µM, IC50, eeAChE = 2.08 µM) and 3t (IC50, eqBChE = 0.82 µM, IC50, eeAChE = 2.38 µM) exhibited more potent dual AChE/BChE inhibitory activities compared with other compounds. Computational modeling results indicated that compounds 3l and 3t could bind to cholinesterase through hydrogen bonds and π-π stacking interactions. Moreover, they displayed potent neuroprotective properties and anti-apoptotic effects in mouse hippocampal HT22 cells. Importantly, the cell cytotoxicity and acute toxicity assays (1000 mg/kg) in mice confirmed that compounds 3l and 3t possessed an acceptable safety profile. The 3l and 3t were identified by the evaluation at the enzyme level and the cellular level, which are expected to be the privileged scaffolds for the development of dual AChE/BChE inhibitors.

Erucamide/thermoplastic polyurethane blend with low coefficient of friction, high elasticity and good mechanical properties for intelligent wearable devices

AbstractIn this study, erucamide as a non‐toxic and tasteless lubricant was melt blended with thermoplastic polyurethane (TPU) to reduce the coefficient of friction (COF) of TPU and thus to improve the wearing comfort of intelligent wearable devices. The results show that when the content of erucamide reaches percolation, erucamide can migrate to the TPU surface, forming a layer of lubrication film, and thus significantly reduces the COF of TPU. In addition, erucamide with amide groups can form hydrogen bonds with carbamate groups from TPU chains and thus can disrupt the hydrogen bonds between two amide groups of TPU chains. With the introduction of erucamide, the chain mobility of TPU increases, the partial phase mixing of soft phase and hard phase of TPU occurs, and the interchain interaction between TPU chains decreases. Under the appropriate content of erucamide (0.5 wt%), both the elasticity and processability of TPU are also significantly improved, whereas the high tensile strength, tear strength and elongation at break of the TPU blend is still obtained, facilitating its practical application in intelligent wearable devices. © 2022 Society of Industrial Chemistry.

Immobilization of a cellulose carbamate-type chiral selector onto silica gel by alkyne-azide click chemistry for the preparation of chiral stationary chromatography phases

A new synthesis strategy for the preparation of cellulose derivative-based chiral selectors and the subsequent mild immobilization onto pre-functionalized silica gel are introduced, utilizing Cu(I)-catalyzed alkyne-azide Huisgen cycloaddition (“click”) chemistry. A cellulose 3,5-dimethylphenyl carbamate derivative carrying propynyl carbamate groups was prepared by a combination of carbonate aminolysis and isocyanate chemistry. For immobilization, 3-azidopropyl-functionalized silica gel as an inert carrier was used, synthesized via a 3-chloropropyl intermediate. The chiral selector, as well as the inorganic/organic hybrid materials (silica gel/chiral selector), were comprehensively characterized by ATR-FTIR, solid-state 13C and 29Si NMR, liquid-state NMR, GPC, TGA, and elemental analysis. The enantioseparation performance of the immobilized-type chiral stationary phase was evaluated by HPLC with a set of representative chiral test analytes and different eluents and compared to a respective coated-type (=non-covalently bound) chiral stationary phase carrying the same selector quality and quantity on the same silica gel matrix. The immobilization did not adversely affect the chiral separation performance; on the contrary, in some chromatographic separations the immobilized-type chiral stationary phase surprisingly even surpassed the coated reference material.Graphical abstract

Study of failure behaviors of rigid polyurethane foam treated under thermal and vibration conditions by experiment and numerical simulation

AbstractFailure mechanism of rigid polyurethane foam (RPUF) treated under different conditions was studied by means of experiments and numerical simulation. Thermal degradation mechanism of RPUF under different temperatures was characterized by thermogravimetric analysis‐Fourier transform infrared spectrometry coupled with gas chromatography–mass spectrometry (TG‐FTIR‐GC–MS) in air and nitrogen atmosphere, respectively. And the vibration failure mechanism of RPUF was analyzed by finite element analysis (FEA) and extended finite element method (XFEM). The experimental results indicated that the failure mode in nitrogen was the broken of carbamate groups, and in air was the broken of carbamate groups and the radical decomposition of ether groups. Numerical simulation suggested that there was vibration stress concentration in the center of foam prism, which was easy to produce sliding and opening fatigue cracks during random vibration.

Polysiloxane-Based Polyurethanes with High Strength and Recyclability.

Polysiloxanes have attracted considerable attention in biomedical engineering, owing to their inherent properties, including good flexibility and biocompatibility. However, their low mechanical strength limits their application scope. In this study, we synthesized a polysiloxane-based polyurethane by chemical copolymerization. A series of thermoplastic polysiloxane-polyurethanes (Si-TPUs) was synthesized using hydroxyl-terminated polydimethylsiloxane containing two carbamate groups at the tail of the polymer chains 4,4′-dicyclohexylmethane diisocyanate (HMDI) and 1,4-butanediol as raw materials. The effects of the hard-segment content and soft-segment number average molecular weight on the properties of the resulting TPUs were investigated. The prepared HMDI-based Si-TPUs exhibited good microphase separation, excellent mechanical properties, and acceptable repeatable processability. The tensile strength of SiTPU-2K-39 reached 21.5 MPa, which is significantly higher than that of other flexible polysiloxane materials. Moreover, the tensile strength and breaking elongation of SiTPU-2K-39 were maintained at 80.9% and 94.6%, respectively, after three cycles of regeneration. The Si-TPUs prepared in this work may potentially be used in gas separation, medical materials, antifouling coatings, and other applications.

Iron-Catalyzed Cross-Electrophile Coupling of Inert C–O Bonds with Alkyl Bromides

Iron-Catalyzed Cross-Electrophile Coupling of Inert C–O Bonds with Alkyl Bromides

Design, Synthesis and Biological Evaluation of Biscarbamates as Potential Selective Butyrylcholinesterase Inhibitors for the Treatment of Alzheimer's Disease.

As butyrylcholinesterase (BChE) plays a role in the progression of symptoms and pathophysiology of Alzheimer’s disease (AD), selective inhibition of BChE over acetylcholinesterase (AChE) can represent a promising pathway in treating AD. The carbamate group was chosen as a pharmacophore because the carbamates currently or previously in use for the treatment of AD displayed significant positive effects on cognitive symptoms. Eighteen biscarbamates with different substituents at the carbamoyl and hydroxyaminoethyl chain were synthesized, and their inhibitory potential toward both cholinesterases and inhibition selectivity were determined. The ability of carbamates to cross the blood–brain barrier (BBB) by passive transport, their cytotoxic profile and their ability to chelate biometals were also evaluated. All biscarbamates displayed a time-dependent inhibition with inhibition rate constants within 10−3–10−6 M−1 min−1 range for both cholinesterases, with generally higher preference to BChE. For two biscarbamates, it was determined that they should be able to pass the BBB by passive transport, while for five biscarbamates, this ability was slightly limited. Fourteen biscarbamates did not exhibit a cytotoxic effect toward liver, kidney and neuronal cells. In conclusion, considering their high BChE selectivity, non-toxicity, ability to chelate biometals and pass the BBB, compounds 2 and 16 were pointed out as the most promising compounds for the treatment of middle and late stages of AD.

Recyclable nanocomposites for carbon dioxide fixation and membrane separation using waste polycarbonate

In this study, polymer nanocomposite membranes with recyclability were developed to achieve good mechanical properties and gas permeability in the consumption of a recycled polymeric material. The newly developed process has been realized through the conversion of waste PC to afford key intermediates containing alkoxysilane and phenolic groups. The alkoxysilanes would act as the nucleation sites for sol–gel reactions, whereas the phenolic groups further provided active hydrogens for click reactions in the production of polyurethane/silica (PU/SiO2) nanohybrids, exhibiting microcavity to facilitate gas molecules diffusion for membrane with improved gas permeability. Moreover, the additional use of aliphatic polycarbonate polyol provided enhanced CO2 solubility for gas separation membranes of the PU/SiO2 nanohybrids with a PCO2 permeability of 24.02 barrer and a selectivity of 32.85 (αCO2/N2), which approached the 2008 Robeson upper bounds. Moreover, the joint presence of polycarbonate polyol and silica in the nanohybrids led to high-performance elastomeric properties, with tensile strengths of 35.5 MPa and over 700 % elongation at break, results that exceeded those of previously reported PU-based gas separation membranes. Notably, this PC recycling process featured the newly formed carbamate groups as the reaction sites, enabling the recyclability of PU/SiO2 nanohybrids as the gas separation membranes for CO2 capture and storage in post-consumption materials.

Detection and risk associated with organochlorine, organophosphorus, pyrethroid and carbamate pesticide residues in chicken muscle and organ meats in Jordan

The aims of this study were to: i) analyze the prevalence and concentration of pesticides belonging to 4 major classes, namely organochlorines, organophosphates, carbamates and pyrethroids in chicken meat, liver and kidney; ii) evaluate the impact of boiling, frying and freezing on pesticide levels in chicken meat, and iii) estimate the dietary exposure to pesticide residues in chicken meat and conduct a risk assessment. Liquid chromatography-mass spectrophotometry (LC – MS/MS) was used to determine the concentrations of pesticide residues in samples. A total of 300 domestic (local) and imported samples were collected from the marketplace in Jordan. About 2.3%, 48.3%, 83%, and 46.3% of the samples exceeded MRLs for the organochlorine, organophosphorus, carbamate and pyrethroid pesticide groups, respectively. About 90% of the local and imported muscle samples and almost all the local and imported liver samples contained one or more pesticide above the MRL. Among all the samples tested, two pesticides, namely deltamethrin and fenoxycarb, occurred in high concentrations. Domestic samples were observed to have higher concentrations of pesticides compared to their imported counterparts. The pesticides concentrations decreased by about 50, 75 and 15% after boiling, frying and freezing, respectively. Risk assessment has shown that there is no potential risk from consuming chicken meat, however, local chicken meat is of more concern than is imported product. This study will help food control authorities develop appropriate regulations regarding the use of pesticides in Jordan.