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Application of fertilizers is a routine method in agriculture to increase the fertility of plants However, conventional fertilizers have raised serious health and environmental problems in recent years. Therefore, the development of biodegradable superabsorbent hydrogels based on natural polymers with the capability for fertilizer controlled release has attracted much interest. In the current research, a novel nanocomposite hydrogel based on gelatin and carboxymethyl cellulose polymers enriched with an iron based metal- organic framework (MIL-53 (Iron)) was prepared. The prepared nanocomposite hydrogel was loaded with NPK fertilizer to obtain a slow release fertilizer system. The structural properties of the nanocomposite hydrogel were investigated using FTIR, XRD, and SEM techniques. The swelling and fertilizer release behavior of the nanocomposite hydrogel were evaluated in conditions. Results showed that by adding iron-based metal organic framework to the hydrogel matrix, the water absorption capacity of the hydrogel system was increased to 345.8 (g/g). Fertilizer release studies revealed that the release of fertilizer from the nanocomposite matrix has a slow and continuous release pattern. Therefore, the synthesized nanocomposite has an appropriate strength and high potential to be used as a slow-release fertilizer system.

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In this study, new slow release fertilizer encapsulated by superabsorbent nanocomposite was prepared by in-situ graft polymerization of sulfonated-carboxymethyl cellulose (SCMC) with acrylic acid (AA) in the presence of polyvinylpyrrolidone (PVP), silica nanoparticles and nitrogen (N), phosphorous (P), and potassium (K) (NPK) fertilizer compound. The prepared materials were characterized by FT-IR, XRD and scanning electron microscopy (SEM) techniques. The incorporation of NPK fertilizer into hydrogel nanocomposite network was verified by results of these analyses. Also, the swelling behavior in various pH and saline solutions as well as water retention capability of the prepared hydrogel nanocomposite was evaluated. The fertilizer release behavior of the NPK loaded hydrogel nanocomposite was in good agreement with the standard of Committee of European Normalization (CEN), indicating its excellent slow release property. These good characteristics revealed that the hydrogel nanocomposite fertilizer formulation can be practically used in agricultural and horticultural applications.

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Despite several excellent properties including low shrinkage, good chemical resistance, curable at low temperatures and the absence of byproducts or volatiles, epoxy resins are susceptible to ultra violet (UV) damage and their durability is reduced substantially when exposed to outdoor environments. To overcome this drawback, UV absorbers have been usually used to decrease the rate of UV degradation. In this present study, the effects of UV light on the chemical, mechanical and physical properties of cured epoxy structure, as well as the effect of an organic UV absorber, Tinuvin 1130, on the epoxy properties were investigated. Chemical changes in a cured epoxy system as a result of the presence and absence of Tinuvin 1130 were determined using Fourier transform infrared spectroscopy (FT-IR) analyses. The effect of Tinuvin 1130 on the surface morphology of the epoxy systems was also investigated by scanning electron microscopy (SEM) imaging. Additionally, the glass transition temperatures (Tg) before and during UV radiation were measured. After an 800 h UV radiation, mechanical test results revealed that the lack of the UV absorber can lead to a ~30% reduction in tensile strength. However, in the presence of Tinuvin 1130, the tensile strength was reduced only by ~11%. It was hypothesized that the use of Tinuvin 1130, as an organic UV absorber in the epoxy-amine system, could decrease the undesirable effects, arising from exposure to UV light.

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The sodium alginate-g-poly(acrylic acid-co-acrylamide)/rice husk ash (NaAlg-g-P(AA-co-AAm)/RHA) superabsorbent nanocomposite was synthesized by the free-radical graft copolymerization of alginate (NaAlg), acrylic acid (AA), acrylamide (AAm), and RHA in aqueous solution. FTIR spectra revealed that the monomers were grafted onto NaAlg chains, and the nanocomposite was formed successfully. Incorporation of RHA into hydrogel matrix formed porous interlinked channels within hydrogel network. Superabsorbent nanocomposite showed greater equilibrium swelling capacity (1070g/g) compared with neat hydrogel (830g/g). Moreover, water transport mechanism of all hydrogels was non-Fickian diffusion type. Rheological measurements confirmed effective role of RHA in improving gel strength of superabsorbent nanocomposite. The influence of various factors, such as different loads (0.3, 0.6, 0.9 psi), solution pH, saline solution, and temperature on the swelling behavior of hydrogels was also assessed. Superabsorbent nanocomposite exhibited good pH-dependent swelling reversibility and high water retention capability, making it more efficient water-saving material for agricultural and horticultural applications.

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Coronary artery disease (CAD) is still the leading cause of death throughout the world. Metal stents are used to widen narrowed arteries. In addition, drug-eluting stents (DES) are widely implanted to decrease the risk of in-stent restenosis. Commercially available polymer-based DES suffer from some limitations. To avoid these drawbacks, the use of self-assembled monolayers (SAMs) in DES has recently been investigated. In this study, methyl- and carboxyl-terminated mixed SAMs on gold (Au) surfaces were successfully prepared. The samples were characterized using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), and contact angle goniometry (CA). The mixed SAM-coated surfaces were evaluated for everolimus delivery. The drug release in PBS was studied using high performance liquid chromatography (HPLC) and quartz crystal nanobalance (QCN). The results were compared with those related to homogenous SAM-coated surfaces. Significant differences (p<0.05) were found in the amount of drug eluted between the mixed SAM and the homogenous one. The findings are promising for the application of mixed SAMs in DES.

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Quartz crystal nanobalance (QCN) technique is considered as a powerful mass sensitive sensor for monitoring of materials in the sub-nanogram level. In the current study, a method based on QCN technique developed to determine Telone in air. Various coating materials including methyl phenyl silicon, 75% phenyl (OV25) and molecularly imprinted polymer (MIP) were employed. The frequency shift of OV25-modified quartz crystal was found to be linear against organohalogen compounds [Telone (soil fumigant), Koril (Herbicide), Endosulfan (organochlorine insecticide) and Chloroform (solvent)] concentrations in the range of 2.4 to 48 mg L(-1) for Telone vapor and 4.8-24 mg L(-1) for three other vapors. The correlation coefficients for Telone, Koril, Endosulfan and Chloroform were 0.992, 0.996, 0.989 and 0.991, respectively. The principal component analysis was also utilized to process the frequency response data of the organic vapors. Using principal component analysis, it was found that more than 93.85% of the data variance could still be explained by use of two principal components (PC1 and PC2). Subsequently, the successful discrimination of Telone and other compounds was quite possible through the principal component analysis of the transient responses of the OV25-modified electrode. In the second method, a molecularly imprinted polymer-coated sensor for Telone was developed. Molecularly imprinted polymer coated quartz crystal (MIP-QCN) showed a selective response to Telone and gave a linear relationship between frequency shift and amount of Telone from 1 to 48 mg L(-1). In this investigation, the proficiency of MIP-QCN and OV25-modified QCN sensors were compared.

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Quartz crystal nanobalance (QCN) sensors are considered as powerful mass sensitive sensors to determine materials in the sub-nanogram level. In the first part of this study, a single piezoelectric QCN modified with polypyrrole (PPy) has been tested for detection and determination of nickel ions in the solution at room temperature. The developed method was successfully applied for detection of total nickel in samples taken from several hot springs located at the Northwest of Iran. The frequency shifts were linear with respect to the concentration of nickel in solution. Using this method, nickel can be measured in the range of 3-20 mg L(-1). A lower limit of detection of 0.79 mg L(-1) and a sensitivity factor of 4.429 Hz/mg L(-1) were obtained. Some possible interference such as heavy metal ions (lead, mercury, and cadmium) was checked. No major interference was observed with the performance of the sensor except for mercury. To evaluate the ability of the PPy-modified QCN in discriminating between nickel ions and interfering mercury ions, a principal component analysis (PCA) was carried out. PCA was utilized to process the frequency response data of the single piezoelectric crystal at different times, considering different adsorption-desorption dynamics of nickel and interfering mercury ions on electrode. Using PCA, it was found that about 97.90% of the data variance could still be explained by two principal components (PC1 and PC2). The score plot of the data for the first two PCs showed that the PPy-modified QCN yields favorable identification and quantification performances for nickel ions. The accuracy of method for hot spring samples was evaluated and RSD of 4.10% was obtained.

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A polystyrene coated quartz crystal nanobalance (QCN) sensor was developed for use in the determination of a number of linear short-chain aliphatic aldehyde and ketone vapors contained in air. The quartz crystal was modified by a thin-layer coating of a commercial grade general purpose polystyrene (GPPS) from Tabriz petrochemical company using a solution casting method. Determination was based on frequency shifts of the modified quartz crystal due to the adsorption of analytes at the surface of modified electrode in exposure to various concentrations of analytes. The frequency shift was found to have a linear relation to the concentration of analytes. Linear calibration curves were obtained for 7-70 mg l(-1) of analytes with correlation coefficients in the range of 0.9935-0.9989 and sensitivity factors in the range of 2.07-6.74 Hz/mg l(-1). A storage period of over three months showed no loss in the sensitivity and performance of the sensor.

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Homovanillic acid (HVA) and vanillylmandelic acid (VMA) were selectively determined by quartz crystal nanobalance sensor in conjunction with net analyte signal (NAS)-based method called HLA/GO. An orthogonal design was applied for the formation of calibration and prediction sets including HVA, VMA, and some common and structurally similar urine compounds. The selection of the optimal time range involved the calculation of the NAS regression plot in any considered time window for each test sample. The searching of a region with maximum linearity of NAS regression plot (minimum error indicator) and minimum of predicted error sum of squares value was carried out by applying a moving window strategy. Based on the obtained results, the differences on the adsorption profiles in the time range between 1 and 300 s were used to determine mixtures of compounds by HLA/GO method. Several figures of merit like selectivity, sensitivity, analytical sensitivity, and limit of detection were calculated for both compounds. The results showed that the method was successfully applied for the determination of VMA and HVA.

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The aim of the present investigation was to develop a biosensor based on a quartz crystal nanobalance (QCN) for the detection of histidine (His). A thin layer of nickel was electrochemically deposited over the gold crystal electrode and exposed to H(2)O(2) to form nickel oxide. The composite electrode was then used to determine His. The frequency shifts were linear with respect to the concentration of His in solution. His can be measured in the range of 100-2000 mg L(-1). A lower limit of detection of 48 mg L(-1) and a sensitivity factor of 0.0307 Hz/mg L(-1) was obtained. Some possible interferences were checked for, and the performance of the sensor was found to be unaffected by any interference except for those from arginine, cysteine and NaH(2)PO(4). Principal component analysis (PCA) was used to process the frequency response data of the single piezoelectric crystal at various times, considering the different adsorption-desorption dynamics of His and the interfering compounds. Over 85% of the variance in the data was explained by two principal components. A score plot of the data for the first two PCs showed that the modified QCN yields favorable identification and quantification performances for His and the interfering compounds.

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