On the preparation and swelling properties of hydrogel nanocomposite based on Sodium alginate-g-Poly (acrylic acid-co-acrylamide)/Clinoptilolite and its application as slow release fertilizer

A novel slow release fertilizer hydrogel nanocomposite was prepared via free radical polymerization of sodium alginate, acrylic acid, acrylamide, and clinoptilolite using N, N?-methylene bisacrylamide as a crosslinker and ammonium persulfate as an initiator. Evidence of grafting and component interactions was obtained by a comparison of the Fourier transform infrared spectra of the initial substrates and hydrogel without clinoptilolite with that of the hydrogel nanocomposite containing clinoptilolite. The swelling behavior of both hydrogels in solutions of various pHs (2-12) and various saline solutions such as NaCl, KCl, CaCl₂ and FeCl₃ as well as swelling kinetics were investigated. Results showed that the swelling of hydrogels depends on the solution pH value. Also, the swelling of both hydrogels in all salt solutions is significantly lower than that of the values in distilled water. After those characterizations, the potential application was verified through sorption and fertilizer releasing from the hydrogel with and without clinoptilolite zeolite. The presence of the clinoptilolite zeolite in the hydrogel caused the system to liberate the nutrient in a more controlled manner than that with the neat hydrogel. The results of the fertilizer release of hydrogel nanocomposite were also encouraging in order to find applications in agriculture. Consequently, the good slow release fertilizer property as well as the good water adsorption capacity showed that this formulation is potentially viable to be used in agriculture as a nutrient carrier vehicle.     

Pressure-Induced Frequency Lineshifts in the nu2 Band of Ammonia: An Experimental Test of the Rydberg-Ritz Principle

The hemolytic lectin, CEL-III, is a Ca2+-dependent, galactose/N-acetylgalactosamine-specific lectin purified from the marine invertebrate, Cucumaria echinata (Holothuroidea). After binding to specific carbohydrates on the erythrocyte surface, CEL-III forms ion-permeable pores by oligomerizing in the membrane, which leads to colloid osmotic rupture of the cells. When incubated with liposomes composed of total lipids from the human erythrocyte membrane, CEL-III efficiently induced the leakage of carboxyfluorescein (CF) trapped in the vesicles, suggesting the presence of its receptor in the membrane lipids. The rate of CF-leakage increased with increasing temperature, although the hemolytic activity of CEL-III had been found to be much higher at lower temperatures (around 10 degrees C). Identification of the receptor for CEL-III was performed by examining the ability of individual lipids from human erythrocytes to induce CF-leakage from DOPC-liposomes. As a result, the most effective receptor was found to be lactosyl ceramide (LacCer), while globoside (Gb4Cer) also showed slight induction of CF-leakage. On the other hand, a binding assay involving CEL-III-horseradish peroxidase conjugate indicated that CEL-III exhibits similar affinity for LacCer and Gb4Cer, suggesting that the structure or length of the carbohydrate portion of sphingoglycolipids is also relevant as to their ability to induce CF-leakage in addition to their affinity. Electron micrographs of CEL-III-treated liposomes revealed that CEL-III induced considerable morphological changes in the vesicles, while a clearly distinguishable oligomeric structure of the protein was not observed.     

An investigation into the relationship between rainfall and road accident frequencies in two cities

A statistical analysis has been made of the effect of moderate and heavy rainfall on accident frequencies recorded for London and Huddersfield (England) for a period of 1 yr. The analysis attempts to measure and compare these effects separately in (a) four specific periods of the day (night, rush hours, mid-day and rest-of-day; defined later); (b) four seasons of the year; and (c) the complete period under study (whole-year analysis).     

Characterization of indoor time reversal UWB communication systems: Spatial,temporal and frequency properties

In this paper, an indoor UWB communications system that applies time reversal (TR) for transmitting the desired signal is proposed. First we define equivalent channel model of TR‐UWB, which is the convolution of channel impulse response and its complex conjugate time‐reversed version. Then spatial, temporal and frequency characteristics of equivalent channel are analyzed and the analytical or semi‐analytical results are validated by comparing measurements with simulation. (Semi) analytical expression of equivalent channel transfer function, TR UWB power delay profile (PDP), focusing gain, spatial correlation and power azimuth spectrum (PAS) is performed. Also probability density function (PDF) of TR‐UWB amplitude and path‐gain is derived. Analysis and simulation results of different distributions, such as uniform, Laplacian and Gaussian for PAS, are considered and presented. It is shown that uniform and truncated Laplacian distributions are appropriate fits to the measurement results for power azimuth spectrum of TR‐UWB. It is seen that for distances greater than λ/2 from the authorized receiver, received signal decreases 10 dB, where λ is the wavelength of the central frequency. Finally, PDF of TR‐UWB path‐gain is described. Measurement results show that for small time windows, the densities of the path‐gain are highly non‐Gaussian. But for starting time of 10T_w or more, and window size of 2T_w or more the densities are nearly Gaussian, where T_w is the transmitted pulse duration. Copyright © 2010 John Wiley & Sons, Ltd.     

Common FABP4 Genetic Variants and Plasma Levels of Fatty Acid Binding Protein 4 in Older Adults

We examined common variants in the fatty acid binding protein 4 gene (FABP4) and plasma levels of FABP4 in adults aged 65 and older from the Cardiovascular Health Study. We genotyped rs16909187, rs1054135, rs16909192, rs10808846, rs7018409, rs2290201, and rs6992708 and measured circulating FABP4 levels among 3190 European Americans and 660 African Americans. Among European Americans, the minor alleles of six single nucleotide polymorphisms (SNP) were associated with lower FABP4 levels (all p ≤ 0.01). Among African Americans, the SNP with the lowest minor allele frequency was associated with lower FABP4 levels (p = 0.015). The C-A haplotype of rs16909192 and rs2290201 was associated with lower FABP4 levels in both European Americans (frequency = 16 %; p = 0.001) and African Americans (frequency = 8 %; p = 0.04). The haplotype combined a SNP in the first intron with one in the 3′untranslated region. However, the alleles associated with lower FABP4 levels were associated with higher fasting glucose in meta-analyses from the MAGIC consortium. These results demonstrate associations of common SNP and haplotypes in the FABP4 gene with lower plasma FABP4 but higher fasting glucose levels.     

Fragility, DSC and elastic moduli studies on tellurite–vanadate glasses containing molybdenum

Ternary xMoO₃–40TeO₂–(60 − x)V₂O₅ glasses with 0 ? x ? 60 (in mol%) have been prepared by normal melt quenching method. DSC curves of these glasses have been investigated. The glass transition properties that have been measured and reported in this paper, include the glass transition temperature (T_g), glass transition width (ΔT_g), heat capacity change at glass transition (ΔC_P) and calculated fragility (F). Thermal stability, Poisson’s ratio, fragility and glass forming tendency of these glasses have been evaluated, to determine relationship between chemical composition and the thermal stability or to interpret the structure of glass. In addition, Makishima and Makenzie’s theory was applied for calculation of Young’s modulus, bulk modulus and shear modulus, indicating a strong relation between elastic properties and structure of glass. Generally, results of this work show that glass with x = 60 has the highest shear, bulk and Young’s moduli which make it as suitable candidate for the manufacture of strong glass fibers in technological applications; but it should be mentioned that glass with x = 20 has higher handling temperature and super resistance against thermal attack.     

Estimation of the Threshold in Energy and Kurtosis Detectors for IR-UWB OOK Systems

In this paper, we propose a method to estimate the threshold value for energy detector (ED) and kurtosis detector (KD) in impulse radio ultra-wideband on-off keying (OOK) scheme. Estimation of threshold value is obtained from the parameters of the probability density functions (PDF) of two hypotheses in OOK signaling. Gaussian and lognormal distributions are used for ED receiver and KD receiver, respectively. Symbols are transmitted in packets and the PDF’s parameters of the hypotheses are estimated by using training symbols in each packet. The approximation of the threshold value is obtained by using these parameters. Simulation results show that the estimated threshold has high accuracy for different amounts of signal to noise ratios and integration intervals.     

Dual responsive polymeric bionanocomposite gel beads for controlled drug release systems

Scientists are searching potential solutions for cancer treatments as well as ways to avoid the side effects of anti‐cancer agents, via targeted drug delivery. The aim of this research is to propose dual responsive beads based on sodium alginate (SA), methylcellulose (MC), and magnetic iron oxide nanoparticles (MIONs) for controlled release of 5‐Fluorouracil (5‐FU) as model drug. The beads were prepared by the dual crosslinking of SA and MC in the presence of MIONs. The structural, thermal, morphological, magnetic characteristics as well as the release profile of 5‐FU were studied. The characterization results showed that the drug molecules and MIONs were well dispersed in the polymeric matrix. The cumulative release percentage was ca. 80% at pH = 4.2 and 40% at pH = 7.2 after 6 h. Thus, the sensitivity of beads on the pH value was verified. Moreover, the release profile exhibited reduction with an increase in the concentration of MIONs under an external magnetic field. The obtained results confirmed the dual sensitive release of 5‐FU (i.e., PH/magnetic) that can be used for the targeted and controlled drug delivery systems. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45143.     

Controlled release of protein from magnetite–chitosan nanoparticles exposed to an alternating magnetic field

In this research, the controlled release of proteins from magnetite (Fe₃O₄)–chitosan (CS) nanoparticles exposed to an alternating magnetic field is reported. Fe₃O₄–CS nanoparticles were synthesized with sodium tripolyphosphate (TPP) molecules as a crosslinking reagent. Bovine serum albumin (BSA) was used as a model protein, and its controlled release studied through the variation of the frequency of an alternating magnetic field. The results show the successful coating of CS and BSA on the Fe₃O₄ nanoparticles with an average diameter of 50 nm. Intermolecular interactions of TPP with CS and BSA were confirmed by Fourier transform infrared spectroscopy. The application of low‐frequency alternating magnetic fields to such magnetic CS nanoparticles enhanced the protein release properties, in which the external magnetic fields could switch on the unloading of these nanoparticles. We concluded that enhanced BSA release from nanoparticles exposed to an alternating magnetic field is a promising method for achieving both the targeted delivery and controlled release of proteins. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43335.