Sr Fe12-xNixO19 nanoparticles(x = 0–1) were synthesized by a combustion sol–gel method. Their structure, dielectric and magnetic properties were investigated by X-ray diffraction(XRD), scanning electron microscopy(S...Sr Fe12-xNixO19 nanoparticles(x = 0–1) were synthesized by a combustion sol–gel method. Their structure, dielectric and magnetic properties were investigated by X-ray diffraction(XRD), scanning electron microscopy(SEM), an LCR metry, and vibrating sample magnetometry(VSM).The results reveal that all samples of Ni doped compounds(Sr Fe12-xNixO19) with x < 0.2 are single phase. It appears that the Fe3+ ions are substituted by Ni2+ ions on the crystallographic sites of the Sr Fe12O19 structure; however, for x ≥ 0.2, the secondary Ni phase ferrite(Ni Fe2O3) appears, which reduces the saturation magnetization and coercivity. In addition, Ni doping reduces the dielectric constant, dielectric loss, and alternating current(ac) electrical conductivity of the samples. The variation in ac conductivity(σac) with frequency shows that the electrical conductivity in these ferrites is mainly attributed to the electron hopping mechanism.Therefore; all the single-phase Ni doped samples are suitable for use in magnetic recording media and microwave devices.展开更多
Challenges in nanoscale characterization call for non-invasive, yet sensitive subsurface characterization of low-density materials such as polymers. In this work, we present new evidence that mode-synthesizing atomic ...Challenges in nanoscale characterization call for non-invasive, yet sensitive subsurface characterization of low-density materials such as polymers. In this work, we present new evidence that mode-synthesizing atomic force microscopy can be used to detect minute changes in low-density materials, such as those engendered in electro-sensitive polymers during electron beam lithography, surpassing all common nanoscale mechanical techniques. Moreover, we propose 3D reconstruction of the exposed polymer regions using successive high-resolution frames acquired at incremental depths inside the sample. In addition, the results clearly show the influence of increasing dwell time on the depth profile of the nano-sized exposed regions. Hence, the simple approach described here can be used for achieving sensitive nanoscale tomography of soft materials with promising applications in material sciences and biology.展开更多
Alzheimer’s disease (AD) is considered a slow neuronal dysfunction process through hypoxia, ischemia and leads to apoptosis mediated senile plaques and neurofibrillary tangles (NFTs). Due to non-invasive approach of ...Alzheimer’s disease (AD) is considered a slow neuronal dysfunction process through hypoxia, ischemia and leads to apoptosis mediated senile plaques and neurofibrillary tangles (NFTs). Due to non-invasive approach of plaque characterization, computational techniques based on Brownian dynamics simulation are unique to speculate the electrostatic and kinetic properties of Acetylcho-linesterase (AChE). Typically the MRI spectros-copy high choline peak and enzyme specific to Alzheimer’s Disease (specificity constant (kcat/Km) of AChE) appeared associated with apoptosis and hypoxia. A simple display between synergy of cytokines, apoptosis, elevated AChE and choline is postulated as initial events. The events may be distributed heterogeneously within the senile plaques and neurofibrillary tangles (NFTs) of Alzheimer’s Disease (AD). The role of decreased brain AChE and synergy was associated with specific Magnetic Resonance Spectroscopic (MRS) pattern profiles in AD. These findings suggest that that the altered AChE and early apoptosis events in AD may be associated with specific MR spectral peak patterns. This study opens the possibility of reduced AChE levels causing high choline and reduced N-acetyl ace-tate (NAA) neurotransmitter by MRS after initial apoptosis and/or inflammation to make amyloid plaques in the cerebral tissue of Alzheimer’s disease (AD) patients. These results can be useful in clinical trials on AD lesions.展开更多
基金Shahid Chamran University of Ahvaz for providing us with financial support for this project
文摘Sr Fe12-xNixO19 nanoparticles(x = 0–1) were synthesized by a combustion sol–gel method. Their structure, dielectric and magnetic properties were investigated by X-ray diffraction(XRD), scanning electron microscopy(SEM), an LCR metry, and vibrating sample magnetometry(VSM).The results reveal that all samples of Ni doped compounds(Sr Fe12-xNixO19) with x < 0.2 are single phase. It appears that the Fe3+ ions are substituted by Ni2+ ions on the crystallographic sites of the Sr Fe12O19 structure; however, for x ≥ 0.2, the secondary Ni phase ferrite(Ni Fe2O3) appears, which reduces the saturation magnetization and coercivity. In addition, Ni doping reduces the dielectric constant, dielectric loss, and alternating current(ac) electrical conductivity of the samples. The variation in ac conductivity(σac) with frequency shows that the electrical conductivity in these ferrites is mainly attributed to the electron hopping mechanism.Therefore; all the single-phase Ni doped samples are suitable for use in magnetic recording media and microwave devices.
文摘Challenges in nanoscale characterization call for non-invasive, yet sensitive subsurface characterization of low-density materials such as polymers. In this work, we present new evidence that mode-synthesizing atomic force microscopy can be used to detect minute changes in low-density materials, such as those engendered in electro-sensitive polymers during electron beam lithography, surpassing all common nanoscale mechanical techniques. Moreover, we propose 3D reconstruction of the exposed polymer regions using successive high-resolution frames acquired at incremental depths inside the sample. In addition, the results clearly show the influence of increasing dwell time on the depth profile of the nano-sized exposed regions. Hence, the simple approach described here can be used for achieving sensitive nanoscale tomography of soft materials with promising applications in material sciences and biology.
文摘Alzheimer’s disease (AD) is considered a slow neuronal dysfunction process through hypoxia, ischemia and leads to apoptosis mediated senile plaques and neurofibrillary tangles (NFTs). Due to non-invasive approach of plaque characterization, computational techniques based on Brownian dynamics simulation are unique to speculate the electrostatic and kinetic properties of Acetylcho-linesterase (AChE). Typically the MRI spectros-copy high choline peak and enzyme specific to Alzheimer’s Disease (specificity constant (kcat/Km) of AChE) appeared associated with apoptosis and hypoxia. A simple display between synergy of cytokines, apoptosis, elevated AChE and choline is postulated as initial events. The events may be distributed heterogeneously within the senile plaques and neurofibrillary tangles (NFTs) of Alzheimer’s Disease (AD). The role of decreased brain AChE and synergy was associated with specific Magnetic Resonance Spectroscopic (MRS) pattern profiles in AD. These findings suggest that that the altered AChE and early apoptosis events in AD may be associated with specific MR spectral peak patterns. This study opens the possibility of reduced AChE levels causing high choline and reduced N-acetyl ace-tate (NAA) neurotransmitter by MRS after initial apoptosis and/or inflammation to make amyloid plaques in the cerebral tissue of Alzheimer’s disease (AD) patients. These results can be useful in clinical trials on AD lesions.
