Synthesis and characterization of poly(vinyl phosphonic acid) (PVPA)-Fe3O4 nanocomposite

Poly(vinyl phosphonic acid) (PVPA)-Fe₃O₄ nanocomposite is synthesized by the precipitation of Fe₃O₄ in the presence of PVPA. Structural, surface, morphological, thermal properties and conductivity characterization/evaluation of the nanocomposite were performed by XRD, FT-IR, TEM, TGA and conductivity measurements respectively. The capping of PVPA around the Fe₃O₄ nanoparticles was confirmed by FT-IR spectroscopy, the interaction being via bridging oxygens of the phosphate and the nanoparticle surface. The crystallite and particle size were obtained as 6 ± 2 and 8.7 ± 0.1 nm from XRD line profile fitting and TEM image analysis respectively, which reveal nearly single crystalline nature of the Fe₃O₄ nanoparticles. Magnetic characterization of the bulk magnetite and (PVPA)-Fe₃O₄ nanocomposite reveals that both are in the superparamagnetic state at room temperature. The average magnetic domain size of the nanoparticles has been calculated using the Langevin function, which was fitted to the measured M-H hysteresis curves as 7.6 nm for the nanocomposite. In the nanocomposite, the reduction is due to the adsorption of PVPA onto the magnetite surface, which cancels some of the free spins at the surface causing a magnetically dead layer. Analysis of the conductivity and permittivity measurements revealed the coupling of ionic and polymer segmental motions and strong temperature dependency in the nanocomposite.     

Synthesis of bulk g-C3N4/Bi2WO6 nanocomposite for effective photocatalytic reaction and for antimicrobial activity by hydrothermal method

Research on Chemical Intermediates - Bi2WO6 was modified by adding metallic-free polymer graphitic carbon nitrite-g-C3N4 for efficient photocatalytic performance and also for antimicrobial...     

Electric dipole moments in the MSSM at large tanβ

Within the minimal supersymmetric standard model (MSSM), the large tanβ regime can lead to important modifications in the pattern of CP-violating sources contributing to low energy electric dipole moments (EDMs). In particular, four-fermion CP-violating interactions induced by Higgs exchange should be accounted for alongside the constituent EDMs of quarks and electrons. To this end, we present a comprehensive analysis of three low energy EDM observables—namely the EDMs of thallium, mercury and the neutron—at large tanβ, in terms of one- and two-loop contributions to the constituent EDMs and four-fermion interactions. We concentrate on the constrained MSSM as well as the MSSM with nonuniversal Higgs masses, and include the CP-violating phases of μ and A. Our results indicate that the atomic EDMs receive significant corrections from four-fermion operators, especially when Im(A) is the only CP-violating source, whereas the neutron EDM remains relatively insensitive to these effects. As a consequence, in a large portion of the parameter space, one cannot infer a separate bound on the electron EDM via the experimental constraint on the thallium EDM. Furthermore, we find that the electron EDM can be greatly reduced due to the destructive interference of one- and two-loop contributions with the latter being dominated by virtual staus.     

阴离子对鼠尾草提取物中Ni盐前体绿色合成的NiO纳米粒子磁性和结构性能的影响

采用绿色合成方法,将鼠尾草提取物用作还原和封端剂合成氧化镍纳米颗粒(NiO NPs)。此外,使用各种前驱体合成了NiO NPs,并使用扫描电子显微镜对其形貌进行了分析。利用傅里叶变换红外光谱和粉末X射线衍射(PXRD)对NiO NPs的结构进行了表征,使用振动样品磁强计测量了它们的磁性。PXRD研究表明,所有合成的NiO NPs都表现出具有高结晶度的面心立方相,并且形成了具有高纯度相的NiO。磁化研究结果表明,3种镍盐(乙酸盐、氯化物和硫酸盐)前驱体合成的NiO NPs分别表现出超顺磁、软铁磁和顺磁行为。     

Structurally Enhanced Hydrogel Nanocomposites with Improved Swelling and Mechanical Properties

In this work, structurally enhanced hydrogel nanocomposites based on 2-acrylamido-2 methyl propane sulfonic acid (AMPS)-acrylamide (AAM) copolymer with high hydrophilic group content were prepared by in-situ copolymerization by using different types of clay (montmorillonite, mica and halloysite). Nanocomposite hydrogels were characterized by Fourier-Transform Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD) analyses and determination of swelling degrees of the samples. Mechanical properties of the samples were also investigated by determination of the compressive elastic modulus. It was also found that exfoliated or highly expanded intercalated nanocomposite structure was obtained and clay incorporation into the AMPS-AAM hydrogel structure improved its swelling capacity. The highest swelling capacity (1030 g H₂O/g) was observed for the nanocomposite sample prepared with the montmorillonite amount of 5% (w). Furthermore, mechanical strength of the hydrogels against compression forces was significantly improved by the clay addition. It was found that the type of clay, in other word filler geometry, affected the compressive elastic modulus (E) of the samples. It was concluded that halloysite, which is considered to be a one dimensional (1D) nanotubular filler was less effective to enhance the compressive elastic modulus (E) of such materials compared with the montmorillonite and mica having two dimensional (2D) platelet or disk-like shapes at a particular amount of clay.     

Sensor Platform with a Custom‐tailored Aptamer for Diagnosis of Synthetic Cannabinoids

Synthetic cannabinoids (SCs) are the large group of abused drugs and detection of them is still a challenge. Hence, new methods for analysis of SCs are being investigated. We aimed to develop a novel system for selective analysis of SCs. First, various custom‐tailored aptamers against the target SCs were selected through GO‐SELEX process. Toggling between different SC analytes during successive rounds of selection was performed to generate cross‐reactive aptamers. Then, the amino‐capped aptamers were synthesized and easily attached to the cysteamine‐covered gold electrodes. Analytical parameters and selectivity of the aptasensors were compared by using electrochemical techniques. After comparison of the analytical features and selectivity towards target analytes, one of the aptamers designated as Apta‐1 was chosen for further measurements. The aptasensor was tested by using differential pulse voltammetry technique against JWH‐018 (5‐pentanoic acid), selected as a model for SCs. The linearity and limit of detection were determined as 0.01–1.0 ng/mL and 0.036 ng/mL. Finally, sample application in synthetic urine samples was successfully performed with standard addition method, as confirmed by LC‐QTOF/MS. JWH‐018 (4‐hydroxypentyl), JWH‐073 (3‐hydroxybutyl), JWH‐250 (5‐hidroxypentyl) and HU‐210 were used to test the selectivity of the aptasensor and the system was shown to recognize all these SCs. Also other illegal drugs did not significantly interfere with the signal responses.     

An eco-friendly water mediated synthesis of 1,2,3-triazolyl-2- aminopyrimidine hybrids as highly potent anti-bacterial agents

An elegant and efficient synthesis of novel 1,2,3-triazole fused 2-aminopyrimidine hybrids has been accomplished for the first time in the green solvent viz. water. The hybrid molecules exhibit significant anti-bacterial activity when screened against three human pathogens viz. Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella pneumoniae. In comparison to the commercially marketed drug tetracycline, some of them are equally potent and a few are more potent.     

Engineered 3D tissue models for cell-laden microfluidic channels

Delivery of nutrients and oxygen within three-dimensional (3D) tissue constructs is important to maintain cell viability. We built 3D cell-laden hydrogels to validate a new tissue perfusion model that takes into account nutrition consumption. The model system was analyzed by simulating theoretical nutrient diffusion into cell-laden hydrogels. We carried out a parametric study considering different microchannel sizes and inter-channel separation in the hydrogel. We hypothesized that nutrient consumption needs to be taken into account when optimizing the perfusion channel size and separation. We validated the hypothesis by experiments. We fabricated circular microchannels (r = 400 μm) in 3D cell-laden hydrogel constructs (R = 7.5 mm, volume = 5 ml). These channels were positioned either individually or in parallel within hydrogels to increase nutrient and oxygen transport as a way to improve cell viability. We quantified the spatial distribution of viable cells within 3D hydrogel scaffolds without channels and with single- and dual-perfusion microfluidic channels. We investigated quantitatively the cell viability as a function of radial distance from the channels using experimental data and mathematical modeling of diffusion profiles. Our simulations show that a large-channel radius as well as a large channel to channel distance diffuse nutrients farther through a 3D hydrogel. This is important since our results reveal that there is a close correlation between nutrient profiles and cell viability across the hydrogel. Young Seok Song and Richard L. Lin have contributed equally to this contribution     

High-pressure X-ray diffraction study of tungsten diselenide

Synchrotron X-ray diffraction was used in conjunction with a diamond anvil cell to investigate the properties of a tungsten diselenide (WSe₂) sample to 35.8 GPa at room temperature. By fitting the pressure-volume data to the third-order Birch-Murnaghan equation of state, the bulk modulus, K_0T, of WSe₂ was determined to be 72±1 GPa with its pressure derivative, , being 4.1±0.1. It was also found that the c-direction of the hexagonal structure is significantly more compressible than the a-direction. No phase transformation was clearly observed in the pressure range of our measurements.     

Luminescence properties of Tb implanted ZnO

ZnO [0 0 0 1] crystals were irradiated at room temperature with Tb⁺ ions of 400 keV with fluences from 1×10¹⁶ to 2×10¹⁷ cm⁻². The implanted layer was examined by several methods, including radioluminescence (RL), Rutherford backscattering spectrometry (RBS) and optical spectroscopy. The optical extinction spectra were simulated using Mie scattering theory. Absorption spectra predicted by Mie theory for particles of decreasing diameter were compared with those obtained experimentally. Some qualitative agreement between theoretical and experimental data was achieved. It was also shown that the intensities of the characteristic green emission bands associated with Tb produced by ⁵D₄→⁷F_j=5,4 transitions have increased about 8 times after annealing. Optical spectroscopy and radioluminescence data have revealed that the ion implantation is a promising tool for synthesizing Tb nanoparticles in the ZnO surface. The Tb nanoparticles exhibit a rather weak plasma resonance.