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BACKGROUND Zinc (Zn) deficiency and low soil fertility are the major factors responsible for low yield in chickpea. This study was conducted to evaluate the effect of Zn application and plant growth-promoting bacteria (PGPB) (endophyte Enterobacter sp. MN17) on soil health and aboveground biomass of desi and kabuli chickpea under natural field conditions. Zn was applied as seed priming (0.001 mol L-1 ) and soil application (10 kg Zn ha-1 ) with and without PGPB. To determine the impacts of Zn and PGPB on soil biological health, soil microbial biomass carbon (MBC) and soil extracellular enzyme activities were analyzed at two growth stages: vegetative (90 days after sowing) and maturity (163 days after sowing). RESULTS The highest aboveground biomass (5.1 t ha-1 ) was recorded with Zn seed priming + PGPB in kabuli chickpea and in desi chickpea (4.8 t ha-1 ) with Zn seed priming only. The application of Zn significantly increased soil MBC, which was higher in kabuli (795 and 731 μg C g-1 ) compared to desi chickpea (655 and 533 μg C g-1 ) at both vegetative and reproductive growth stages, respectively. The highest extracellular soil enzyme activities, - β-glucosidase (4758 nmol g-1 h-1 ), acid phosphatase (5508 nmol g-1 h-1 ), chitinase (5997 nmol g-1 h-1 ) and leucine aminopeptidase (993 nmol g-1 h-1 ) - were recorded with Zn seed priming. Of the chickpea types, kabuli chickpea had higher soil extracellular enzyme activities in the rhizosphere than desi chickpea. CONCLUSION Zn seed priming along with PGPB application may improve soil health and chickpea biomass in marginal soils. © 2021 Society of Chemical Industry.

The bulk quantity of poultry manure (PM) and buffalo dung (BD) is generated by the growing poultry industry and buffalos in Pakistan that causes serious environmental issues such as air, water, and land pollution. Nutrient leaching, mainly nitrogen, phosphorus contaminates soil and water bodies, ammonia evaporation results in air quality degradation, and pathogen contamination affects the health of flora and fauna. This research study aims to utilize PM and BD for biogas generation to meet the energy requirement of the people and save the environment that was degraded due to improper disposal of selected waste. The anaerobic co-digestion technique was used for the treatment of poultry manure and buffalo dung. The ratio selected was 3:1, 1:3, and 1:1 in 500-ml glass bottles acting as digesters. The PM and BD were used in a separate digester. All the digesters have a retention time of 63 days and operated at a temperature of 37 °C and 45 °C. The detailed experimental work shows that 1:3 ratio of PM and BD yield 561 Nml/gm.VS. The quality of the biogas generated from 1:3 of PM and BD digester was also maximum among all five digesters; the volumetric composition of biogas obtained was methane 64% and carbon dioxide 32%. From this study, it was observed that the digestion of a single substrate is less productive as compared with co-digestion; co-digested substrate gives more quantity and quality of biogas, higher biodegradability of biomass, and effective volatile solids (VS) removal.

A series of polyfunctional benzoxazine monomers containing aromatic and fluorene group (AMFB) were used as modified agents to improve the performance of typical bifunctional bisphenol-A-aniline-based (BA-a) benzoxazine resins. The polymerization behaviors of BA-a/AMFB blends were investigated by using the differential scanning calorimetry (DSC), while the dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) were used to analyze the thermomechanical and thermal properties of BA-a/AMFB copolymers [poly(BA-a/AMFB)]. Moreover, the cross-section morphologies of poly(BA-a/AMFB) were observed by scanning electron microscope (SEM). The experimental results showed that BA-a monomer has good catalytic activity for AMFB monomers during the curing process. Compared with BA-a polymer [poly(BA-a)], due to the introduction of heat-resistant fluorene ring and the increase of the crosslinking degree of copolymers, the copolymers showed higher glass transition temperature and better thermal properties. For poly(BA-a/AMFB), the T5, T10, and Yc were higher than those of poly(BA-a). With the increase of the alkyl chain length of AMFB monomers, the cross-section creases gradually changed from linear to dendritic, and the number of creases increased significantly, which indicated that the toughness of the copolymers was significantly improved.

Recently, the discharge of effluent containing dyes and other chemicals into river, lakes, and land has become a serious problem which increases the pollution level drastically. The dyes in the effluent are very difficult to be removed by conventional water treatment methods. Thus, there is a great need for more advanced methods that are cost-effective and more efficient. In this study, silver nano particles (AgNps) were synthesized by green method using extracts of onion (O), tomato (T), acacia catechu (C) alone, and mixed COT extracts. The reduction and formation of AgNps and its ions have been characterized by using several techniques, Ultra visible spectroscopy (UV–vis), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM)-energy dispersive X-ray spectrometer (EDX), Fourier transmission infrared spectroscopy (FTIR), and dynamic light scattering (DLS). These techniques revealed that the particle sizes of synthesized AgNps in all the extracts were ranged in between 5 and 100 nm with a crystalline nature. The synthesized AgNps were used as catalysts for the degradation of three different types of dyes, methyl orange (MO), methyl red (MR), and congo red (CR) in the liquid state. The excellent catalytic application of all the synthesized AgNps on the degradation of the studied dyes was confirmed via UV–visible results by studying the reduction in the absorbance maxima value within a very short interval of time. COT synthesized products were found to achieve the best performance for all dyes degradation among all products.

There is a rising concern for the rapid increase of COVID-19 confirmed cases in Kandahar province. From zero reported cases until 17th March 2020, then Kandahar saw a sudden rise in the cases by 16th May 2020. Decreased literacy rates, poor health education, lack of facilities, inconsistent government policies, and defying coronavirus safety advisory by the public have resulted in the rapid spread of COVID-19. The awareness and practices of the people towards the COVID-19 were significantly low. Therefore, the risk of coronavirus in Kandahar province is extremely high due to the aforementioned reasons. To overcome this virus, the local government must declare strict measures and provide the public with information about the severity and prevention mechanisms of this fatal disease. Mass and random diagnostic testing are required to track the actual infection rates, which can give a realistic picture of what is occurring. In this article, the current situation of COVID-19, available medical facilities, and public response to the ongoing pandemic in Kandahar, Afghanistan was highlighted. Key words: COVID-19, Kandahar province, public response, curfew, random testing.

Increasing financialization of energy and commodity markets offer a variety of tradeoff for the investors and consumers. On the one hand, this increased financialization of the two markets helps investors design a well-diversified investment portfolio with assets from different asset categories. However, at the same time, this increases the connectedness between the two markets significantly, which may have strong implications for investors and consumers. In this paper, we examine the long-term connectedness and causality between Crude oil and agricultural commodity prices. The advantage of long-term time series is that we may be able to uncover the demand and supply shocks that originated in both markets during the tranquil period and the shocks during the volatile period such as the Global Financial Crisis of 2008 and COVID-19 pandemic. For this purpose, we employ the full bootstrap sample and rolling window causality tests primarily. Our results are surprisingly different from most of the studies that have held oil prices responsible for causing changes in agricultural commodity prices (ACP). In contrast, our results confirm the presence of bidirectional causality and show that Oil prices are as much affected by the ACP as vice versa. This significant reverse causality running from ACP to Oil prices can open up a completely new interpretation domain. Finally, it is surprisingly interesting that both ACP and Oil prices remain immune to the shocks that originated in both markets during the entire time period of the COVID-19 pandemic.

In this paper, 2,7-dihydroxy-9,9-bis(4-aminophenyl)-fluorene (BADHF) monomer was synthesized via direct condensation reaction catalyzed by methylsulfonic acid. A novel allylamine-based benzoxazine monomer containing fluorene rings and polymerizable groups (t-BF-sa-a) was obtained using the o-hydroxy-benzyl amine method combined with a one stage Mannich condensation reaction. The results showed that the introduction of fluorene rings and polymerizable groups and the increase of the number of oxazine rings in the polymer network structure can result in an obvious increase in the crosslinking density of the polymers. Therefore, t-BF-sa-a polybenzoxazine (poly(t-BF-sa-a)) exhibited a higher glass transition temperature (Tg) and better thermal stability. The synthesized t-BF-sa-a monomer was used to modify traditional phenol-aniline-based mono-functional (P-a) and bisphenol A-aniline-based bifunctional (BA-a) benzoxazines. Due to the introduction of heat-resistant fluorene rings and the increase of the crosslinking degree of the copolymers, the copolymers (poly(P-a/t-BF-sa-a) and poly(BA-a/t-BF-sa-a)) showed excellent thermal properties. Among them, the Tg, T5, T10, and Yc of poly(P-a/t-BF-sa-a) were increased by 34 °C, 58 °C, 35 °C, and 8%, respectively, which are even higher than those of bisphenol fluorene aniline-based polybenzoxazine. Furthermore, due to the long alkyl chain in the t-BF-sa-a monomer, the E′ values of the copolymers were decreased significantly, which greatly improved the shortcomings of traditional polybenzoxazines, such as high brittleness and poor toughness.

This manuscript aimed to examine the impact of the hybridization process of hybrid fibers consisting of carbon and basalt fibers on the properties of thermosetting resin blends composed of dicyanate ester of bisphenol-A (DCBA) and bisphenol-A based benzoxazine (BA-a) resins. According to data gathered, the mechanical properties of the hybrid fibers reinforced the DCBA/BA-a blend composites were chiefly improved when compared to the base samples’ properties, while the hybridized composites showed much enhanced thermal stability degradation at higher temperatures. The shielding evaluations disclosed that the integration of the hybrid fibers helped the DCBA/BA-a blend to possess excellent nuclear shielding properties. With respect to the properties of the as-used reinforcing systems, performing the structural and morphological analyses permitted us to prove that the enhanced quality of the reinforcing agents inside the thermoset resin blend was possibly behind these ameliorations in the investigated performances.

Dianshan Lake (DSL) as an important water source protection area in Shanghai is facing serious water quality deterioration. A detailed investigation of persistent organic pollutants (POPs) including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs) in the multiphase system of DSL is very important for understanding their occurrence, sources, partition, and health risks. Total 11 sampling sites were selected including 3 inflowing rivers, 6 lake body sites, and 2 outflowing rivers. Total OCPs (Σ20OCPs) showed the highest concentration in water dissolved phase with a range of 47.8–143 ng/L. Total PAHs (Σ16PAHs) were the dominant compounds for suspended particle matter (SPM) and sediment phase, with a range of 2805–4130 and 206–4262 ng/g, respectively. The nonparametric test revealed the significantly higher concentrations of Σ16PAHs in sediment, Σ18PCBs in SPM, and Σ20OCPs in dissolved water from inflowing rivers than lake body (p Σ20OCPs (67.4 ± 27.0 ng/g) > Σ18PCBs (32.0 ± 13.7 ng/g), with obvious species-specific characteristics. The partitioning behaviors of PAH congeners in the water-SPM-sediment-fish system of DSL were greatly influenced by logKow values. However, the feeding habits (e.g., sediment-feeding behavior) of fish species played a predominant role in the bioaccumulation of PCB and OCP congeners compared to two-phase partition. Health risk assessments of POPs in dissolved water and fish samples revealed that only Σ16PAHs in dissolved phase have potential carcinogenic risk.

The clue of this present work reported in this manuscript was to combine the properties of thermosetting resin blends composed of dicyanate ester of bisphenol-A (DCBA) and bisphenol-A based benzoxazine (BA-a) resin with those of short glass fibers in order to produce novel functional materials. To achieve this objective, various amounts of short glass fibers were surface modified using the silanization technique, sandwiched within the DCBA/BA-a resin blend using the hand-up lay technique, and then cured using the compression molding technique under the pressure of 25 MPa. The characterisation of the produced composites was experimentally conducted by performing the structural, morphological, mechanical, and thermal analyses. According to the mechanical results, the tensile, bending and impact strength results revealed that the addition of the fibers assisted the DCBA/BA-a resin composites to possess superior mechanical properties over the pure polymers. The thermal stabilities of the DCBA/BA-a resin composites were also substantially improved and were noticeably higher to a large extent than those of the unfilled resin blends. These aforementioned enhancements were further investigated by performing the Fourier Transform Infrared Spectroscopy and the scanning electron microscopy analyses that showed good dispersion and interfacial adhesion between the different constituents of the produced materials. Therefore, the distinguished mechanical and thermal properties promote the use of the manufactured composites in domestic and industrial applications requiring functional polymers with advanced properties such as aerospace and military applications.

In the current study, the epoxy/amine system is reinforced by the biodegradable Acacia Catechu (AC) particles on 0.5, 1.0, 1.5 and 2.0 wt (wt.) %. The AC/epoxy composites were characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), scanning electron microscope (SEM), and mechanical properties. The increased hydrogen bonding for the AC/epoxy composites was observed by FTIR spectroscopy and DSC study confirmed the improved conversion of epoxy after the AC particles addition. 14% increase in the flexural strength and 94% improved impact strength were recorded on only 1.0 wt. % AC addition due to change in morphology and crosslink density. Moreover, slightly improved thermal stabilities were also recorded due to the aromatic tannin phenol structures of AC particles. The glass transition temperature values for AC/epoxy composites were observed at 143 and 148 °C by DSC and DMA, respectively; the decline in the values can be dedicated to the flexible segment of AC particles. The SEM analysis demonstrated shear banding phenomena between particles and matrix.

Metribuzin (MB) is used for control of weeds in crops like potato, maize and sugarcane. Its extensive and unjudicial use has resulted in various environmental issues; hence it is very critical to remediate this herbicide at the respective point source. Plant associated, MB degrading bacterial strains, Rhodococcus rhodochrous sp. AQ1, Bacillus tequilensis sp. AQ2, Bacillus aryabhattai sp. AQ3 and Bacillus safensis sp. AQ4 were isolated, and a consortium MB3R was developed. For degradation of MB by the consortium MB3R, various parameters i.e., pH, temperature, inoculum density and pesticide concentration were optimized by using Taguchi design of experiment (DOE). MB degradation was dependent upon all the four factors. The contribution of each factor on MB degradation was according to the order: temperature > inoculum density > pH > pesticide concentration. Fitness of Taguchi DOE in forecasting the optimum response, was confirmed experimentally by using optimized levels of the four factors i.e., pH 7.0, temperature 30 °C, pesticide concentration 45 mg l−1 and an inoculum density of 5.0 × 10 5 CFU ml−1 whereby 98.63% MB degradation was observed. Appearance and subsequent degradation of three MB metabolites, desamino-metribuzin (DA), diketo-metribuzin (DK) and desamino-diketo-metribuzin (DADK) during biodegradation by the consortium was observed.

This present study details an experimental investigation on understanding the effects of surface-modified waste hemp fibers on the overall properties of thermosetting resin blends composed of dicyanate ester of bisphenol-A and bisphenol-A-based benzoxazine resins. At first, the hemp fibers were subjected to sodium bicarbonate treatment, and then various experimental tests in terms of the Fourier-transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis tests were, respectively, carried out to understand the influence of the as-used treatment on the structural, morphological, and thermal properties of the hemp fibers. The obtained results from the surface characterization evidently demonstrated the positive sodium bicarbonate impacts on the properties of the hemp fibers. After that, various amounts of the treated fibers were incorporated within the dicyanate ester of bisphenol-A/bisphenol-A-based benzoxazine resin blends and the obtained composite materials were characterized for their structural, mechanical behavior and thermal properties. The obtained results clearly revealed that the prepared blend composites were identified to possess good bending and impact strength properties; however, a slight decline was observed in the thermal properties. The scanning electron microscopy and Fourier-transform infrared spectroscopy investigations demonstrated a good dispersion of the fibers within the blend matrix, and also an enhanced fiber–blend matrix interfacial adhesion, which were plausibly behind the improved mechanical properties of the prepared blend composites.

Understanding fluid flow in shale rocks is critical for the recovery of unconventional energy resources. Despite the extensive research conducted on water and oil flow in shales, significant uncertainties and discrepancies remain in reported experimental data. The most noted being that while oil spreads more than water on shale surfaces in an inviscid medium, its uptake by shale pores is much less than water during capillary flow. This leads to misjudgement of wettability and the underlying physical phenomena. In this study, therefore, we performed a combined experimental and digital rock investigation on an organic-rich shale including contact angle and spontaneous imbibition, X-ray and neutron computed tomography, and small angle X-ray scattering tests to study the potential physical processes. We also used non-equilibrium thermodynamics to theoretically derive constitutive equations to support our experimental observations. The results of this study indicate that the pre-existing fractures (first continuum) imbibe more oil than water consistent with contact angle measurements. The overall imbibition is, however, higher for water than oil due to greater water diffusion into the shale matrix (second continuum). It is shown that more water uptake into shale is controlled by pore size and accessibility in addition to capillary or osmotic forces i.e. configurational diffusion of water versus oil molecules. While the inorganic pores seem more oil-wet in an inviscid medium, they easily allow passage of water molecules compared to oil due to the incredibly small size of water molecules that can pass through such micro-pores. Contrarily, these strongly oil-wet pores possessing strong capillarity are restricted to imbibe oil simply due to its large molecular size and physical inaccessibility to the micro-pores. These results provide new insights into the previously unexplained discrepancy regarding water and oil uptake capacity of shales.

Cresyl diphenyl phosphate (CDP), as a kind of aryl substituted organophosphate esters (OPEs), is commonly used as emerging flame retardants and plasticizers detected in environmental media. Due to the accumulation of CDP in organisms, it is very important to discover the toxicological mechanism and metabolic process of CDP. Hence, liver microsomes of crucian carps (Carassius carassius) were prepared for in vitro metabolism kinetics assay to estimate metabolism rates of CDP. After 140 min incubation, the depletion of CDP accounted for 58.1%–77.1% (expect 0.5 and 2 μM) of the administrated concentrations. The depletion rates were best fitted to the Michaelis-Menten model (R2 = 0.995), where maximum velocity (Vmax) and Michaelis-Menten constant (Km) were 12,700 ± 2120 pmol min−1·mg−1 protein and 1030 ± 212 μM, respectively. Moreover, the in vitro hepatic clearance (CLint) of CDP was 12.3 μL min−1·mg−1 protein. Log Kow and bioconcentration factor (BCF) of aryl-OPEs were both higher than those of alkyl- and chlorinated-OPEs, indicating that CDP may easily accumulate in aquatic organisms. The results made clear that the metabolism rate of CDP was greater than those of other OPEs detected in liver microsomes in previous research. This paper was first of its kind to comprehensively investigate the in vitro metabolic kinetics of CDP in fish liver microsomes. The present study might provide useful information to understand the environmental fate and metabolic processes of these kinds of substances, and also provide a theoretical basis for the ecological risk assessment of emerging contaminants.

Shallow urban lakes are important urban ecosystems; however, these systems are subject to severe polycyclic aromatic hydrocarbons (PAHs) contamination. An understanding of the distribution and dynamics of PAHs in lakes is required to restore the functions of lake ecosystems and to ensure the ecological security of urban water sources. The Quantitative Water Air Sediment Interaction (QWASI) model and partition coefficient and fugacity fraction methods were applied to estimate the multimedia transfers of PAHs in Dianshan Lake, a typical shallow lake in Shanghai, China. In addition, some new concepts and methods related to PAH transfers were introduced. The results showed that while the gas-solid partition in the area remained in non-equilibrium, the influence of pollution sources tended to weaken. Atmospheric advection was the main source of PAHs to the lake, and a portion of the net loss of advection was transformed into total flux of cross-interface transfers, in which transport fluxes from air to water and from water to sediment were dominant, with a significant correlation between the two types of transfer. The large resuspension of high molecular weight (HMW)-PAHs occurred, possibly related to frequent hydrodynamic disturbances. Furthermore, this study explored the distribution of PAHs among different compartments and the seasonal variation of multimedia transfers. Sensitivity analysis showed that the model is remarkably sensitive to four parameters including temperature and advection. Monte Carlo uncertainty analysis verified that the simulation results were stable and reliable. The results can provide a theoretical basis for the monitoring and control of shallow lake pollution.

PM2.5 samples in four representative periods were collected from a highly industrialized district in Shanghai, China. The concentrations of PM2.5 and PM2.5-bound PAHs were analyzed. Positive matrix factorization (PMF) model was used to identify the potential sources. Relationship between PAHs distribution and meteorological parameters was assessed meanwhile. The incremental lifetime cancer risks (ILCRs) model was applied to quantitatively evaluate the exposure risk of PAHs. Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLT) model was used to track the potential pollution area of PM2.5 along with a Potential Source Contribution Function (PSCF) and Concentration Weighted Trajectory (CWT) methods. The results showed concentrations of PM2.5 and PAHs ranged from 14.83 to 185.58 μg/m3, 2.58 to 123.62 ng/m3, respectively. The source apportionment model indicated that traffic emissions were the most important sources in each sampling season, which accounted for 38.44%, 34.48%, 39.04% and 45.03%, respectively. Spearman correlation coefficient showed that PAHs had negative correlation with ambient temperature and relative humidity in some periods, while had no significant correlation with atmospheric pressure and visibility. The average estimated lifetime cancer risk for total PAHs reached 4.7 × 10−5, 4.5 × 10−5 and 4.1 × 10−5, 4.0 × 10−5 to exposed children and adults in winter and autumn, respectively, meaning that PM2.5-bound PAHs had high potential risk. HYSPLIT model suggested that monsoon greatly influenced the air quality in both winter and autumn.

In this present work, silane modified acacia catechu particles (MACPs) filled dicyanate ester of bisphenol-A/bisphenol-A based benzoxazine (DCBA/BA-a) blend composites were successfully prepared by a simple and environmentally friendly solution blending method. The main focus of this study was to investigate the influence of the modified particles on the overall morphological, mechanical and thermal properties of the blend composites using various tests. The FTIR analysis confirmed the surface modification of the acacia catechu particles. Besides, it showed the nature of the chemical interactions taking place between the modified particles the resin blend. According to the mechanical results, a remarkable increase in the tensile, impact strength and microhardness properties of the reinforced blend composites was chiefly observed as compared to the unfilled samples' properties. Based on the thermal stability studies, the filled blend composites showed much enhanced thermal resistance properties. The scanning electron microscope confirmed that the improvements in the investigated properties were essentially ascribed to the good dispersion and interfacial adhesion of the modified particles within the blend matrix with respect to their advanced properties. Therefore, we supposed herein that these eco-friendly acacia catechu particles have enough potential to be utilized as alternative fillers for producing naturally friendly blend composites with tailored properties.

The eugenol based phthalonitrile (EPN) monomer was successfully copolymerized with mono and difunctional benzoxazine (P-a and BA-a) monomers via concerted catalysis polymerization. The loading of EPN in benzoxazine monomers was varied from 10 to 40 wt% and impacts of loading on thermal, thermomechanical and mechanical properties were studied. The FTIR analysis confirmed that both poly(P-a/EPN) and poly(BA-a/EPN) copolymers can be completely cured without the addition of curing additive. The addition of the bio-based EPN monomer enhanced the curing peak temperatures and reduced the curing reaction enthalpies. Initially, OH groups were produced from the oxazine ring opening polymerization of benzoxazine and they enhanced the curing of EPN. The thermal stabilities, as well as the stiffness and Tg of the copolymers, were much higher as compared to the neat polymers. Highest values were seen on the 40 wt% loading of EPN monomer in the copolymers. Moreover, the difunctional benzoxazine based copolymer showed higher enhancements in the properties as compared to the mono-functional benzoxazine based copolymer. The decline was seen in the flexural properties as EPN monomer contains the flexible chain in the structure. The morphological changes supported all the claims for the copolymers. The prepared copolymers can be used as a high performance thermosetting resin.

This study aims to evaluate the influence of cyclohexane/ethanol, alkali, and silane treatments on the waste hemp fibers and their polybenzoxazine composites. The Fourier transform infrared (FTIR), scanning electron microscope (SEM), and thermogravimetric analysis (TGA) tests were carried out to understand the influence of treatments on the fibers. FTIR results revealed that hemicellulose and lignin of the fibers were removed after washing with cyclohexane/ethanol, and thermal stability of the fibers was improved after the alkali and silane treatments. The consequences of the treatments on the hemp fiber composites were studied by evaluating the mechanical, thermomechanical, thermal, and water uptake properties. The flexural, tensile and impact tests results confirmed that the silane treated fiber composites displayed highest properties than the other treated fiber composites. Furthermore, the stiffness and glass transition temperature of the silane treated fiber composites were also best among the studied composites. Moreover, the thermal stabilities values showed the lowest decline for the silane treated composites; due to the better thermal stability of the silane treated fibers, and lowest water absorption was also recorded for the silane treated fiber composites. The morphological studies confirmed that the silane treated fiber composite had stronger fiber/matrix adhesion interface.

In the present study, the influence of incorporating various amounts of hyperbranched polyester (HBPE) into thermosetting resin blends composed of cyanate ester (CE) and benzoxazine (BOZ) resins was investigated for their structural, morphological, mechanical, and thermal properties. The FTIR spectra revealed that the CE/BOZ resin had reacted with the functional groups of HBPE, and the SEM test confirmed the morphological changes from a smooth surface that was observed for the virgin CE/BOZ resin to a rough surface for the maximum HBPE content. Moreover, the mechanical and thermal properties were found to be pointedly enhanced as we increased the content of HBPE. These remarkable enhancements may be due to the chemical structure of the HBPE which could form a cross-linked structure through a strong hydrogen bonding with the CE/BOZ resin. As a result, a considerable amount of applied mechanical load can be absorbed, and in parallel, the thermal stability can also be improved. We believe that the HBPE can be a good toughener for the CE/BOZ resins that could possibly expand their range of applications in various industrial sectors.

The benzophenone-center bisphenol-A containing phthalonitrile monomer (BBaph) was successfully produced by a nucleophilic substitution reaction of 4,4′-difluorobenzophenone with 4-nitrophthalonitrile and bisphenol-A in the presence of potassium carbonate. The chemical structure of the synthesized monomer was confirmed by 1H nuclear magnetic resonance (1H NMR), 13C NMR, and Fourier transform infrared spectroscopy (FTIR). The curing study of monomer was evaluated by the FTIR and DSC curves. The poly(BBaph) was subjected to gamma-ray irradiation with 100 kGy dose of 60Co gamma radiation. The variation in chemical structure, mechanical, thermomechanical and thermal properties of poly(BBaph) was evaluated by FTIR, flexural, dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA), respectively. All results confirmed very minute deviation in the estimated properties before and after radiation. The BBaph monomer was blended with typical mono-functional benzoxazine (P-a) in different weight ratios. The DSC, DMA, and TGA tests were performed to study the properties of copolymers. The high glass transition temperature (164–227 °C), and stiffness values (2.72–3.03 GPa) was observed for the copolymers. The thermal stability was also improved after the loading of BBaph in P-a, recorded values were in the range of 367–408 °C, and 46.1–58.7% for 5% weight loss temperature and char yield at 800 °C, respectively.

In this current study, alkali treated eco-friendly hemp fibers were chosen to reinforce thermosetting resin blend composed of cyanate ester and benzoxazine resin. For various volume fractions ranging from 5 to 20 vol % with a regular increment of 5 vol%, their effects on the morphological, mechanical behaviour and water uptake properties were experimentally evaluated using the scanning electron microscopy, flexural, tensile and water uptake tests. The produced composites possessed much ameliorated flexural properties as compared to those of the unfilled resin. Data from the tensile test revealed a continuous increase in the composites' tensile strength and modulus as the proportion of the treated fibers augmented. Furthermore, the tensile experimental results were compared to the most commonly used empirical models like the rule of mixture (ROM), revised rule of mixture (RROM), inverse rule of mixture (IROM), Halpin Tsai (HT), Lewis and Nielson (LN), and Halpin Kardos (HK) models. It was found that the alkali treated fibers were arranged in a 3D random fiber arrangement according to the RROM model and the HK model was identified to fit well the tensile experimental results. The experimental results and theoretical modeling confirmed that the water absorption in the produced composites was increased and governed by the Fickian diffusion. These effects took place due to the chemical and morphological changes in the treated fiber external surfaces, which promoted better interfacial adhesion between the plant fibers and the polymer blend matrix.

Two bio-based phthalonitrile (PN) monomers, eugenol-based phthalonitrile (EPN) and guaiacol-based phthalonitrile (GPN), were successfully synthesized by the reaction of 4-nitrophthalonitrile with eugenol and guaiacol derived from clove and lignin, respectively, in the presence of potassium carbonate via nucleophilic substitution reaction. Their chemical structures were confirmed by the Fourier transform infrared spectra (FTIR), hydrogen and carbon nuclear magnetic resonances (1H and 13C NMR), and elemental analysis. The curing behavior of the blends of the prepared PN monomers with 10 wt% of 4-(4-aminophenoxy)-phthalonitrile (4-APN) as curing agent was evaluated by FTIR and differential scanning calorimetry (DSC), while rheometer was used to analyze the processability of the blends. Moreover, the thermomechanical and thermal properties of the polymers were studied by dynamic mechanical analyzer (DMA) and thermogravimetric analysis (TGA). The results confirmed that the bio-based PN monomers and its blends show low melting temperatures, wide processing windows (>186 °C), and low melt viscosity (

A new tetra-nuclear sulphate bridged complex (Cu4(SalTCB)4(SO4)2) was prepared based on benzyl 2-(2-hydroxybenzylidene)-1-methylhydrazine-1-carbodithioate (SalTCB) ligand and characterized by IR, UV–vis spectroscopy, HR ESI-MS, elemental analysis and single crystal X-ray. Solid-state X-ray results revealed that this complex was a sulphate-bridged macrocycle interwoven from four Cu2+ and four ligand molecules. The coordination property of SalTCB to Cu2+ was investigated as selective colorimetric Cu2+ sensor in buffered aqueous-acetonitrile. This sensing property was studied in detail by different spectroscopic analysis. The limit of detection (LOD) for Cu2+ was as low as 0.51 μM. Similarly, ChrDTCB solution based methodology was developed that afforded instant naked eye detection of Cu2+.

This present study deals with the reinforcement of thermosetting resin blends composed of cyanate ester (CE) and benzoxazine (BOZ) resins with natural hemp fibers (NHFs). These NHFs were initially treated by using a silane coupling agent (SCA) in order to chiefly enhance their distributions as well as adhesions within the CE/BOZ resin matrix, then incorporated with various weight amounts ranging from 5 wt% to 20 wt% with a regular interval of 5 wt%. The obtained results showed that at the maximum treated fiber loading (20 wt%), distinctive enhancements in the mechanical properties in terms of flexural strength and microhardness were obtained. Besides, the thermal stability and glass transition temperature ( T g ) were appreciably enhanced and were higher than those of the pure CE/BOZ resin properties. With respect to the astonishing properties of the NHFs, these enhancements could be possibly due to the good dispersion and adhesion of the treated NHFs inside the CE/BOZ resin achieved upon using the SCA. Therefore, we believe herein that these renewable and cheap NHFs have considerable potential to be used as reinfocer materials for CE/BOZ resin composites to be used in various industrial sectors.

In this paper, various concentrations of silane treated carbon fibers (TCFs) were incorporated within cyanate ester/benzoxazine resin to demonstrate their effects on the morphological, mechanical, thermal decomposition properties of the composites. Mechanical test inferred the distinctive improvements in the values of the flexural strength and modulus. The glass transition temperature (Tg) determined from the DSC measurements were appreciably higher than those of the unfilled blend. TGA results showed an improved in the thermal stability in terms of the T5%, T10%, Yc, THRI and LOI for all composites. For instance, the T5%, T10%, Yc, THRI and LOI were respectively 345.1 °C, 391.8 °C, 50.1%, 217.1 °C and 37.5% for the composites with 20 wt% of the TCFs. The thermal degradation was assessed by evaluating the variation of the activation energy (Eac) of the composites by using three kinetic models, namely Horowitz and Metzger, Coat and Redfern, and Broido models. It was found that the Eac greatly increased and further reflected the improvement in the thermal stability of the composites. This could be attributed the unique characteristics of the TCFs that possibly resulted in effective physical barrier effects against thermal degradation, thereby leading to the amelioration of the thermal properties.

The phthalonitrile resins have claimed the leading place in the field of high performance polymers thanks to their combination of outstanding properties. The present work explores for the first time the gamma rays radiation resistance and shielding efficiency of the phthalonitrile resins and its related tungsten-reinforced nanocomposites. The primary goal of this research is to define the basic behavior of the phthalonitrile resins under highly ionizing gamma rays. The obtained results confirmed that the neat phthalonitrile resins can resist absorbed doses as high as 200 kGy. Meanwhile, the remarkable shielding efficiency of the phthalonitrile polymers was confirmed to be easily improved by preparing lead-free nanocomposites. In fact, the gamma rays screening ratio reached the exceptional value of 42% for the nanocomposites of 50 wt% of nano-tungsten loading. Thus, this study confirms that the remarkable performances of the phthalonitrile resins are not limited to the thermal and mechanical properties and can be extended to the gamma rays radiation and shielding resistances.

The brittleness always remained a major concern for the polybenzoxazine thermosets. Several attempts have been made to overcome the brittleness issue, but all find some kind of sacrificing in other properties. A new and economical approach is presented by the reinforcement of catechin-rich Acacia catechu (AC) particles. The micro size AC particles blended with bisphenol-A aniline-based benzoxazine (BA-a) resin and isothermally cured. The terminal OH groups of produced tannic acid participated in the curing process and helped in the ring opening of BA-a resin. The composites exhibited that the brittleness of polybenzoxazine has been improved by 35%, simultaneously its strength, Youngs’ modulus, stiffness, glass transition temperature, and thermal stabilities are also enhanced. The highest impact strength of the composite is observed on only 4 wt% loading of AC particles and read as 5.2 ± 0.16 kJ/m2, 307.1% higher than the value of neat poly(BA-a).

A high-performance copolymer was successfully prepared by blending bisphenol-A based bisphthalonitrile monomer (BAPh) with phenol-aniline-based benzoxazine monomer (P-a). The obtained copolymers exhibited excellent thermal stability and thermomechanical properties. The Fourier transform infrared (FTIR) spectra of BAPh/P-a 5:5 system at different curing procedure proved the curing reaction mechanism. In addition, differential scanning calorimetry (DSC) curves showed that the curing reaction of the BAPh was induced by the active hydroxyl produced by the ring-opening polymerization of P-a; compared to the neat monomers, the curing temperature of the copolymer decreased and the curing speed improved. The evolution of thermal gravimetric analysis (TGA) curves revealed that the poly(BAPh/P-a)-5:5 displayed highest T5%, T10%, and char yield. The dynamic mechanical analysis (DMA) proved that the glass transition temperature and storage modulus of copolymers with the BAPh monomer as the matrix increased with the content of P-a increase, while copolymers with P-a as the matrix obtained nearly same results. The poly(BAPh/P-a) -5:5 exhibited best thermal and thermomechanical properties among different composition copolymers.

A novel self-exothermic curing agent, effectively able to cure the diglycidyl ether of bisphenol-A (E51 epoxy resin) at room temperature, has been synthesized by blending 4, 4’-diaminodiphenylmethane (DDM) and acrylic acid (AA). The chemical structure of prepared curing agent was characterized by 1 H nuclear magnetic resonance ( 1 H NMR) and Fourier transform infrared (FTIR). The curing behavior of epoxy with synthesized room temperature hardener was studied by differential scanning calorimetry (DSC) and FTIR. Results confirmed that the curing reaction was completed in only 3 h, which can be attributed to the high reactivity of the acryl amide groups with epoxy and high heat release from DDM and AA reaction. The 5 wt% NaOH treated short hemp fibers (TF) were sandwiched in room temperature curing epoxy resin to obtain rapid prototyping high performance composites. The effects of fiber content on the mechanical properties of composites were studied in terms of tensile, flexural, and impact load. The tensile strength of the composites was increased with the increase of the TF content, and the elongation at break was decreased. Compared with the cured neat epoxy resin, an increase of about 233% in impact strength, 52% in flexural modulus, and 213% in Young's modulus were recorded for the cured composite having 7.5 wt% TF content. We used dynamic mechanical analyzer (DMA) and thermogravimetric analysis (TGA) to study the effect of fiber content on the thermal properties of composites. The scanning electron microscope (SEM) revealed excellent adhesion between TF and epoxy resin cured at room temperature.

The waste hemp fibers (HF) were alkali treated; then shredded, ball milled, and sieved. The 20, 40, and 80 mesh collected HF was reinforced in polybenzoxazine. The effects of fiber diameter and vol.% loading on tensile, impact, flexural and water uptake properties of composites have been studied. On 30 vol.% loading of 20 mesh HF, an increase of 91%, 43%, 168%, 137%, and 73% in tensile strength, flexural strength, impact strength, tensile modulus, and flexural modulus, respectively. The additional enhancement was observed in all mechanical properties as fiber diameter was reduced from 311.5 ± 42.9 to 198.3 ± 40.7 μm (20–80 mesh). The similar behavior was confirmed by Halpin-Tsai model. The water uptake was also increased as vol.% loading increased and HF diameter decreased, 28.2% higher water uptake was observed on 20 vol.% loading as the diameter was reduced from 20 to 80 mesh.

In this study, thermosetting resin blends composed of cyanate ester (CE) and benzoxazine (BOZ) were prepared and then subjected to gamma-ray irradiation with doses up to 1000 kGy from a cobalt-60 gamma irradiator. The objective of this present study was to experimentally assess the effect of γ-ray irradiation on the mechanical behaviour, chemical structure and thermal properties of the CE/BOZ resin blends by the bending test, dynamic mechanical analysis (DMA), scanning electron microscopy (SEM), Fourier Transform Infrared (FTIR) and thermogravimetric analysis (TGA). The results showed that at a low radiation dose (250 kGy), the flexural strength and modulus, thermal stability, storage modulus and glass transition temperature of the CE/BOZ resin gradually declined first, then sharply increased when the radiation dose increased to 500 kGy and finally slightly dropped at the end with a dose of 1000 kGy. The decrease in the aforementioned properties could be ascribed to the degradation process including the rupture of chemical bonds and scission of molecular chains of the CE/BOZ resin blends, which were confirmed by the FTIR and SEM. However, a significant improvement in the thermal and mechanical properties of the blend was found when the radiation dose increased to 500 kGy.

Natural fibres (NFs) have been successfully reinforced in polymer matrices to strengthen the properties of the polymers. The polybenzoxazine thermosets are facing instable mechanical properties due to the high brittleness, herein, waste hemp fibres (WHF) reinforced polybenzoxazine composites are prepared. Effects of WHF volume % loading on curing, thermomechanical, mechanical, and thermal properties are studied. FTIR results confirmed that WHF rich in −OH groups increased the ring-opening of oxazines and reduced curing temperature. In addition, an increase of 223%, 111%, 64%, and 253% in impact, tensile strength, flexural and Young's modulus, respectively, were recorded after loading optimum concentration (30 vol. %) in composites. Considerable enhancements were also seen in the thermomechanical properties on optimum loading, double stiffness and 26°C increase was recorded in the glass transition temperature. Nonetheless, the decline was observed in thermal stabilities, T5% and Yc were 24°C and 1....

A series of amino-containing fluorene-based bisphthalonitrile (AFPN) monomers with alkyl or alkoxy groups were successfully produced by the reaction of 4-nitrophthalonitrile with 9, 9-bis (3-alkyl (or alkoxy)-4-aminophenyl)-2, 7-dihydroxylfluorene in the presence of potassium carbonate by a nucleophilic substitution reaction. The chemical structures of the synthesized monomers were confirmed by the Fourier transform infrared (FTIR), proton nuclear magnetic resonance, and carbon-13 nuclear magnetic resonance analyses. The synthesized monomers’ curing behaviors were evaluated by FTIR and differential scanning calorimetry, and a rheological analysis was performed to evaluate their respective processabilities. Moreover, dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) were performed for the thermomechanical, thermal, and thermo-oxidative analyses of the polymers. The results confirmed that the newly prepared phthalonitrile (PN) monomers with alkyl or alkoxy groups exhibited a self-promoted curing behavior. The rheological analysis suggested that the processing windows of the synthesized monomers were wider than that of APFN monomer bearing no flexible group. DMA and TGA revealed that the cured polymers exhibited high glass transition temperature (358–416°C) and the char yields at 800°C under nitrogen were between 70% and 77%. Moreover, the introduction of alkyl or alkoxy groups into the PN monomers’ backbones slightly reduced the thermal stability of the resulting polymers.

A new kind of nanocomposites was prepared from a high performance phthalonitrile resin and Ti3SiC2 MAX phase ceramic nanoparticles. The synergistic combination of both phases led to nanocomposites with improved thermal and mechanical properties. For instance, the thermal conductivity and tensile properties of the neat resin were highly enhanced on adding more nanofillers contents. Moreover, the phthalonitrile resin toughness was enhanced by 123% at the maximum nanoparticles loading of 15 vol.%. The experimental investigations were also compared with predictions from Series, Halpin-Tsai, and Kerner models and a full discussion was provided. A high resolution transmission electron microscope confirmed the ability of the MAX phase to create a conductive network, especially at high nanofillers amounts. SEM analyses of the tensile fractured surfaces revealed positive changes in the morphology, such as an increase in the roughness and amount of hackling as well as the formation of multiple micro-cracks. The MAX phase also enhanced the thermal stability, stiffness, and glass transition temperature of the neat resin. This work confirms the superiority of the MAX phase ceramics over the traditional ones in enhancing the properties of the phthalonitrile resin and opens the way for further research in the field. POLYM. COMPOS., 2017. © 2017 Society of Plastics Engineers

The short length hemp fibers treated with 5% NaOH (THF) were sandwiched in bisphenol A-aniline based benzoxazine (BA-a) to form the resin-fiber-resin composite. The effects of fluctuating fiber volume on the curing behavior, mechanical, thermomechanical, and thermal properties of the resulted composites were studied through fourier transform infrared (FTIR), differential scanning calorimetry (DSC), dynamic mechanical analyzer (DMA), thermogravimetric analysis (TGA), and scanning electron microscope (SEM). The results confirmed that the rich -OH groups on THF can promote the ring-opening of oxazines at lower curing temperature, and improve the adhesion between fiber and matrix. In addition, an increase of 185% in impact strength, 1.3 GPa in flexural modulus, and 109% in tensile strength was recorded for 25 vol% THF content cured composites. The slight diminution in thermal stability was observed as THF content increased, at 25 vol% THF content, weight loss temperature (T5%) and char yield at 800 °C (Yc) were 11 °C, and 0.4% lower than pristine poly(BA-a), respectively.

Cadmium (Cd) is a toxic heavy metal with unknown biological role. Interactive effect of Enterobacter sp. MN17 and biochar was studied on the growth, physiology and antioxidant defense system of Brassica napus under Cd contaminated soil. A multi-metal tolerant endophytic bacterium, Enterobacter sp. MN17, was able to grow in tryptic soy agar (TSA) medium with up to 160, 200, 300, 700, 160 and 400 μg mL−1 of Cd, Cu, Cr, Pb, Ni and Zn, respectively. Paper and pulp waste biochar was prepared at 450 °C and applied to pots (7 kg soil) at a rate of 1% (w/w), while Cd was spiked at 80 mg kg−1 soil. Application of Enterobacter sp. MN17 and biochar, alone or combined, was found effective in the amelioration of Cd stress. Combined application of Enterobacter sp. MN17 and biochar caused the maximum appraisal in shoot and root length (52.5 and 76.5%), fresh and dry weights of shoot (77.1 and 70.7%) and root (81.2 and 57.9%), photosynthetic and transpiration rate (120.2 and 106.6%), stomatal and sub-stomatal conductance (81.3 and 75.5%), chlorophyll content and relative water content (RWC) (78.4 and 102.9%) than control. Their combined use showed a significant decrease in electrolyte leakage (EL), proline, malondialdehyde (MDA), catalase (CAT), glutathione peroxidase (GPX), glutathione S transferase (GST) and superoxide dismutase (SOD) by 39.3, 39.4, 39.5, 37.0, 39.0 42.1 and 30.8%, respectively, relative to control. Likewise, the combined application of bacterial strain MN17 and biochar reduced Cd in soil by 45.6%, thereby decreasing its uptake in root and shoot by 40.1 and 38.2%, respectively in Cd contaminated soil. The application of biochar supported the maximum colonization of strain MN17 in the rhizosphere soil, root and shoot tissues. These results reflected that inoculation with Enterobacter sp. MN17 could be an effective approach to accelerate biochar-mediated remediation of Cd contaminated soil for sustainable production of crops.

Porous flowers-like magnesium oxide (MgO) was prepared using a facile and low-cost method. The structure, morphology and pore properties of prepared MgO were investigated. The results revealed that as-prepared MgO possesses hierarchical flowers-like structural features with a large surface area of 117.48 m2 g−1. Excellent adsorption capacity, towards phosphate and methyl orange, was exhibited by the fabricated MgO having an adsorption capacity of 724 mg g−1 and 1715 mg g−1 for phosphate and methyl orange respectively. The experimental data better fitted the pseudo-second-order and Freundlich isotherm model demonstrating multilayer adsorption of pollutants onto MgO adsorbent with endothermic nature. In five consecutive adsorptions/desorption cycles, the regenerated particles retained their adsorption performance. This work provides a pathway for the large-scale development of efficient adsorbent materials to overcome the sustainable problems.

In this paper, a novel series of tetra-functional fluorene-based benzoxazine monomers (SAMFB) were obtained by o-hydroxy-benzylamine method combining with Mannich condensation reaction. Compared with the traditional three-step method, the synthesis of asymmetric benzoxazine reduced the treatment process of the intermediate product, greatly shortened the reaction time and experimental period, improved the yield of the intermediate product, and reduced the production cost. In the traditional three-step synthesis method, the double bond reduction process took 8–12 h, but in this paper, it only took 15 min to complete this process. The curing characteristics, kinetics, thermal stabilities, and thermomechanical properties of SAMFB monomers and their polymers were analyzed. Non-isothermal curing kinetics studies showed that the polymerization process of SAMFB monomers was an autocatalytic reaction. The introduction of fluorene rings and polymerizable groups and the increase of oxazine rings in the polymer network structure can result in an obvious increase in the crosslinking density of polymers. Therefore, SAMFB polymers (poly(SAMFB)) exhibited higher glass transition temperature (Tg, 314–317 °C) and better thermal stability properties, higher than that of traditional bisphenol A-aniline-based and reported bifunctional fluorene-based polybenzoxazine resins. The TGA results showed that the T5 and T10of poly(SAMFB)were 334−368 °C and 370−414 °C, respectively, and Yc at 800 °C was 45.7–61.6 %. Moreover, the toughness of poly(SAMFB) was greatly improved due to the introduction of the flexible alkyl chain.

Polycyclic aromatic hydrocarbon (PAH) contamination in agricultural soils (n = 41) along Shanghai road net was systematically investigated to characterize pollution distribution and to apportion sources. Total PAH (Σ16PAH) concentrations in roadside agricultural soils varied from 17.2 to 3775 ng/g with an average of 339 ± 594 ng/g, 43.9 % of which corresponded to weakly - heavily contaminated levels. The spatial distribution of pollution hotspots depended on heavy traffic volume and intensive industrial activities in adjacent areas. A positive matrix factorization receptor model identified that vehicle emission and combustion of coal, biomass and natural gas were the predominant sources, accounting for 66.0 % and 23.7 % of Σ16PAH loadings, respectively. Stable carbon isotope analysis was applied for the first time in seven sites with high Σ16PAH concentrations for tracing their unique sources. It was concluded that PAHs in the heavily contaminated soil site G18 predominantly came from vehicle emission sources, different from the six other sites controlled by coal-processing and biomass combustion sources. Future studies should focus on quantifying the source contribution of PAHs in roadside agricultural soils based on the combination of multi-isotope approaches due to the data overlap of δ13C in certain sources.

The present paper concerns the patterns of heavy metals (As, Hg, Pb, Cd, Ni, Zn, Cr, and Cu) in surface soil of residential areas located on derelict brownfields in a city in China and the health risks to the residents. Forty-one surface soil samples were collected from 9 housing units built on different brownfields in a city of Henan Province in China, and the concentrations of heavy metals were measured. Based on the health risk models recommended by the US Environmental Protection Agency (US EPA), carcinogenic and non-carcinogenic health risks of soil heavy metals were assessed. Compared with the original brownfields, soil heavy metal contents and their health risks in housing units built on brownfields have significantly decreased. The contents and health risks of heavy metals in these housing units are all higher than those in non-brownfield housing units. The result of health risk assessment indicates that there are no non-carcinogenic risks and slight carcinogenic risks for the residents in these housing units. The contribution of hazard quotient caused by arsenic (HQ As) to hazard index (HI) is approximately 53%, and the contribution of cancer risk caused by arsenic (CR AS) to total carcinogenic risk (TCR) is approximately 80%. The obtained results have confirmed the environmental effects of brownfields and that soil remediation is an essential step for the redevelopment of brownfields. Arsenic is the crucial heavy metal for carcinogenic and non-carcinogenic risk in the housing units of the city, and the highest levels of non-carcinogenic and carcinogenic risks are associated with the route of ingestion of soil for all heavy metals.

Spatial-temporal distributions, sources identification and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in overlying water and surface sediments in urban river networks of Shanghai were studied. Analytical results showed that there was a significant seasonal variation in concentrations of ∑16PAHs in water, suspended particulate matter (SPM) and sediment phases in this study area. The PAHs pollution in these multi-phases were in the medium level compared with other areas around the world, and the levels of PAHs contamination in SPM and sediment phases in hierarchical rivers showed TS (the third-order stream) > FS (the first-order stream) > SS (the second-order stream). Two manners of isomer ratios and principal component analysis (PCA) were used to identify PAHs origins, and suggested that combustion processes are dominant for PAHs sources. The ratios of PAHs origins by fossil fuels combustion, coke burning and crude oil in hierarchical rivers were determined with FS > SS > TS in SPM and sediment phases, and the ratio of PAHs origins by traffic emissions was analyzed with TS > SS > FS. PAHs in water samples have a certain impact on aqueous ecological system especially due to the fact that the ∑ceq values of nine PAHs were calculated from 0.715 to 15.831 μg/L in winter, which inferred serious ecological risk to some special aquatic organisms. The calculations of MERMQ in sediment samples showed that the MERMQ values ranged from 0.021 to 1.209 in winter and 0.019 to 0.643 in summer, which suggested high toxicity at six sampling sites in winter and only one location in summer due to high levels of PAHs. Furthermore, the toxicity degree of sediments were demonstrated with TS > FS > SS.

Several techniques are available to characterise the wettability of porous rocks wherein the contact angle measurement technique has gained popularity, especially in tight rocks. Recent studies in surface science however raise an important issue on contact angle measurement and its theoretical analysis - whether the contact angle is controlled by the properties of the substrate area underneath the droplet or by the properties of the substrate at the circumference forming the three-phase contact line. This important issue has not been discussed in geomaterial contact angle characterisation despite its significant importance. We, therefore, conducted a series of experiments to study the role of contact area and three-phase contact line on dictating the contact angle. The experiments considered the material heterogeneity (i.e. clay, organic matter, and acrylic), surface roughness and geometry, and its patterns. We also used a new approach using interferometry to investigate the contact angle localisation. The results of this study revealed that the formation of the contact angle is only dictated by the three-phase contact line and not the contact area. No change in contact angle was observed when different materials or surface geometries were introduced under the droplet. The results also suggested that an increase in roughness can lead to erroneous contact angle measurements due to localisation of the contact angle and changes in the three-phase contact line point. The results further showed that the surface pattern plays a major role in contact angle measurement and must be considered if present. Finally, the combined understanding of the results indicated that the current contact angle measurements of geomaterials might carry significant error and that additional methodologies for determining their surface wettability should be used.

Despite significant advances in micro-scale measurement techniques for investigations in subsurface energy-bearing geomaterials, they have been unable to incorporate subsurface geomechanical conditions such as in-situ stresses in their applications. To overcome such lacking, we designed a novel high-pressure shear cell capable of measuring chemo-thermo-mechanical behaviour of actual (not synthetic) geomaterials by allowing application of critical stresses while simultaneously being exposed to different fluids. For assessment of the novel setup, a set of measurements for shale surface and micro-structural alteration due to ionic solution under different states of stress (isotropic/anisotropic) were performed. The system generated accurate results showing that surface swelling on shales is not uniform but rather localized and the cause of fluid-induced microstructural alteration is associated with reduction in rock’s shear strength. Such results highlight the importance of performing rock-related measurements under in-situ stresses which paves way for more application areas that can be potentially benefitted through this setup.

Despite the success of hydrocarbon production from unconventional shale reservoirs, the physical processes controlling the production are not yet fully understood. The wettability controlling the two-phase flow in deformable natural fractures of shale is among the processes that still need special attention. With the advances of optical technologies, microfluidics can now be used to observe, measure, and analyse the dynamic changes of flow in fractured systems. However, mimicking the natural wall roughness of the fractures with high precision and having flexibility to allow fracture deformation has remained challenging. We have therefore developed a new microfluidic technique to create tensile fractures in shale with subsurface representative random geometries and roughness, and then observed two-phase flow in these deformable fractures at a high resolution for Utica shale. During the two-phase flow, dynamic contact angles of water-oil in the fractures with varying apertures of 60–100 μm were measured and analysed. Significant contact angle hysteresis was observed when oil displaced water out of the fracture and vice versa. Interestingly, water completely displaced the oil out of the fracture through spontaneous imbibition, although its contact angle in the fracture varied from 20° to 90°. The water velocity in the fracture was found to be correlated to the observed contact angles during the spontaneous imbibition test. The large change in the contact angle was further investigated using fluorescence tracking where patches of oil were observed to remain on the fracture wall despite its water wetness. It was then shown through further investigations that the formation of these oil patches was primarily controlled by mineral heterogeneity than wall roughness.

In this study, Acacia catechu (AC) extract was used as a stabilizing and reducing agent to synthesize silver (Ag) and titanium dioxide (TiO2) nanoparticles (NPs). By using AC extract, the synthesis process becomes more environmental friendly, economical, and advantageous. The morphology and size of synthesized Ag and TiO2 NPs were determined by X-ray diffraction (XRD), Transmission electron microscopy (TEM), Dynamic light scattering (DLS), Atomic force microscopy (AFM), and Scanning electron microscopy (SEM). Elemental composition was determined by using Fourier transform infrared spectroscopy (FTIR) and Energy dispersive X-ray spectrometer (EDX), EDS mapping and X-ray photoelectron spectroscopy (XPS). The observations from TEM, SEM, AFM, and DLS revealed that synthesized products are spherical, hexagonal, polydispersed, and ranged within 6–20 nm size. XRD result demonstrated well crystallized and smaller size NPs are formed in both cases. FTIR and XPS analysis depicted the presence of flavonoids, terpenoids, and amino groups in addition to benzene ring agents; which act as stabilizing agents as well as possible aromatic primary amine groups may also be attached with the surface of Ag and TiO2 NPs. Furthermore, the synthesized AgNPs exhibited strong antibacterial activity against S-aureus and catalytic application over Rose Bengal, Rhodamine B, and 4 nitrophenol dyes as compared to TiO2 under sunlight (solar irradiation). Overall, Ag and TiO2 NPs exhibit high potential in the development of antibacterial materials for both Gram-positive as well as Gram-negative bacteria and catalytic material for photocatalytic degradation of a certain type of hazardous dyes or chemicals, thereby paving the way for the treatment and bioremediations. The reason could be high energy and smaller size particles were active in the photo-catalysis and antibacterial performance of AgNPs compared to TiO2 NPs.

Two novel quinoxaline-based maleimide monomers, 2,3-diphenyl-6-maleimido-quinoxaline (MQMI) and 2,3-di(2-maleimido)phenyl-quinoxaline (BQMI), were successfully synthesized and characterized. Their structure was confirmed by 1H nuclear magnetic resonance (1HNMR) and Fourier transforms infrared (FTIR). The curing behavior was investigated by the rheological method and Differential scanning calorimetry (DSC). Starink method was used for the curing kinetics analysis of MQMI and BQMI monomers. The curing temperature and the apparent activation energy of BQMI were lower than that of MQMI, which indicated that the maleimide group location could affect its curing behavior. The thermal stabilities of the cured quinoxaline-based maleimide resins were detected by Thermogravimetric analysis (TGA), which implied that their decomposition temperatures were comparable with Poly(4,4’-bismaleimido diphenylmethane) (PBMDPM). However, the char yields (Yc) of PMQMI and PBQMI reached 54.1% and 57.3%, respectively, which were much higher than recorded values of PBMDPM.

Structural variations of a mineral dictate its adsorption capacity which affects the mobility and toxicity of contaminants in natural and engineered systems. Present batch study evaluates the adsorption of lead (Pb) and cadmium (Cd) onto three magnetites having nanometric (M1-30 nm and M2-60 nm) and micrometric particle sizes (M3-1.5 μm). Obtained data revealed that particle size of tested magnetites strongly affected the extent and kinetics of metal adsorption and desorption. Observed order of adsorption efficiency was M1 > M2 > M3 with optimum monolayer adsorption of 408.14, 331.40, 178.47 mg/g (for Pb) and 228.05, 170.86, 83.49 mg/g (for Cd), respectively. Adsorption data were well fitted to the Freundlich (R2 = 0.99), Langmuir (R2 = 0.99) and pseudo-first order models (R2 = 0.98). Electrostatic attraction and surface precipitation interaction via external mass transfer between bulk liquid-solid interfaces were the potential adsorption pathways. Pb showed higher affinity than Cd in multi-metal system. Desorption efficiency was higher in acidic environment (92%) than in distilled water (44%). Moreover, regenerated magnetite samples retained good adsorption capacity for six cycles. As soils are characterized by large variability of iron minerals, these findings have important implications regarding the transport and immobilization of contaminants particularly in the management of contaminated soils.

Metribuzin (MB) is a triazinone herbicide used for the eradication of weeds in agriculture. Presence of its residues in agricultural soil can potentially harm the establishment of subsequent crops and structure of soil microbial populations. In this study, remediation potential of an MB degrading bacterial consortium MB3R immobilized on biochar was evaluated in potato vegetated soil. In potato vegetated soil augmented with MB3R alone and MB3R immobilized on biochar, 82 and 96% MB degradation was recorded respectively as compared to only 29.3% in un-augmented soil. Kinetic parameters revealed that MB3R immobilized biochar is highly proficient as indicated by significant increase in the rate of biodegradation and decrease in half-life of MB. Enhanced plant growth was observed when augmented with bacterial consortium either alone or immobilized on biochar. Presence of herbicide negatively affected the soil bacterial community structure. However, MB3R immobilized on biochar proved to be helpful for restoration of soil bacterial community structure affected by MB. This is the very first report that reveals improved remediation of contaminated soil and restoration of soil bacterial populations by use of the MB degrading bacterial consortium immobilized on biochar.