Characteristics of Conventional and Microwave Sintered Iron Ore Preform

In this study, compacted hematite (Fe₂O₃) preforms were made and sintered at various temperatures, such as 1250 °C and 1300 °C, using both conventional and microwave sintering methods. The density, porosity, microhardness, cold crushing strength, microphotographs, and X-ray diffraction (XRD) analysis of the sintered preforms were used to evaluate the performance of the two sintering methods. It was found that microwave sintered preforms possessed lesser porosity and higher density than conventionally sintered preforms owing to uniform heating of the powdered ore in microwave sintering method. Furthermore, it was also observed that microwave sintered preforms exhibited relatively higher cold crushing strength and hardness than conventionally sintered preforms. Thus, the overall results revealed that microwave sintering yielded better properties considered in the present study.     

An application of multivariate moment-generating functions to the analysis of signal and noise propagation in radiographic screen-film systems

Previous studies [J. Opt. Soc. Am. 4A 895-901 (1987)] have shown the utility of multivariate moment-generating functions for analyzing the influence of stochastic amplifying and scattering mechanisms on the transfer of signal and noise through multistage imaging systems. Recently, these studies were extended to include cases in which the amplification or scattering parameters are themselves stochastic variables [J. Opt. Soc. Am. 6A, 1156-1164 (1989)]. In this paper we consider a special case in which amplification is followed by scattering such that the same random variable which characterizes the parameters of each amplification process also characterizes the parameters of the subsequent scattering of the amplified output events. In radiographic imaging, this can be used to describe the physics of the depth dependence of emission efficiency and light scatter in x-ray intensifying screens, which was originally treated by Lubberts [J. Opt. Soc. Am. 58, 1475-1483 (1968]). In this work Lubberts' original results are rederived in a more general form. They are then illustrated in terms of a diffusion model [Appl. Opt. 12, 1865-1870 (1973)] for light scatter within the intensifying screen.     

The optimization effect of different parameters on the super hydrophobicity of prickly-shaped carbonyl iron particles

In this study, the effects of glucose concentration, temperature, and time parameters of the hydrothermal reaction on the growth of prickly-shaped carbonyl iron were studied by using an experimental design to obtain the maximum superhydrophobicity of the magnetic particles. The experimental design was carried out by Response Surface Methodology (RSM) analysis using the Central Composite Design (CCD) method. Field Emission Scanning Electron Microscopy (FESEM) analysis was performed to qualitatively assess the growth of the prickly-shaped carbonyl iron, and Water Contact Angle (WCA) analysis was used to quantify the superhydrophobicity of the resulting particles. The results revealed that the elevation of the concentration and time increased the roughness (prickly shape) of the particle surface and contact angle up to a point, after which it did not affect them. The temperature elevation caused an increase in the prickly shape of the particles and contact angles and then reduced them. The optimum concentration, temperature, and time were 0.75 Mol L⁻¹, 170 °C, and 4 hours, respectively, for the maximum growth of prickly-shaped particles and the maximum contact angle was 169.7°. Fourier-Transform Infrared Spectroscopy (FT-IR) and thermogravimetric analysis (TGA) results confirmed the presence of glucose and stearic acid chemically bonded to the carbonyl iron particles. The X-ray Diffraction (XRD) results showed that the carbonyl iron had been not converted into iron oxide during the synthesis procedures of the superhydrophobic particles. Vibrating Sample Magnetometer (VSM) analysis showed that making the particles superhydrophobic had little effect on the magnetization reduction.

The effects of glucose concentration, temperature, and time parameters of the hydrothermal reaction on the growth of prickly-shaped magnetic particles were studied by using an experimental design to obtain the maximum superhydrophobicity.     

Intermediate follow-up following intravascular stenting for treatment of coarctation of the aorta.

BACKGROUND: We report a multiinstitutional study on intermediate-term outcome of intravascular stenting for treatment of coarctation of the aorta using integrated arch imaging (IAI) techniques. METHODS AND RESULTS: Medical records of 578 patients from 17 institutions were reviewed. A total of 588 procedures were performed between May 1989 and Aug 2005. About 27% (160/588) procedures were followed up by further IAI of their aorta (MRI/CT/repeat cardiac catheterization) after initial stent procedures. Abnormal imaging studies included: the presence of dissection or aneurysm formation, stent fracture, or the presence of reobstruction within the stent (instent restenosis or significant intimal build-up within the stent). Forty-one abnormal imaging studies were reported in the intermediate follow-up at median 12 months (0.5-92 months). Smaller postintervention of the aorta (CoA) diameter and an increased persistent systolic pressure gradient were associated with encountering abnormal follow-up imaging studies. Aortic wall abnormalities included dissections (n = 5) and aneurysm (n = 13). The risk of encountering aortic wall abnormalities increased with larger percent increase in CoA diameter poststent implant, increasing balloon/coarc ratio, and performing prestent angioplasty. Stent restenosis was observed in 5/6 parts encountering stent fracture and neointimal buildup (n = 16). Small CoA diameter poststent implant and increased poststent residual pressure gradient increased the likelihood of encountering instent restenosis at intermediate follow-up. CONCLUSIONS: Abnormalities were observed at intermediate follow-up following IS placement for treatment of native and recurrent coarctation of the aorta. Not exceeding a balloon:coarctation ratio of 3.5 and avoidance of prestent angioplasty decreased the likelihood of encountering an abnormal follow-up imaging study in patients undergoing intravascular stent placement for the treatment of coarctation of the aorta. We recommend IAI for all patients undergoing IS placement for treatment of CoA.     

Syzygium aromaticum ethanol extract reduces AlCl_3-induced neurotoxicity in mice brain through regulation of amyloid precursor protein and oxidative stress gene expression

Objective: To investigate the neuroprotective effects of Syzygium aromaticum(S.aromaticum)extract(500 mg/kg) on AlCl_3(300 mg/kg)-induced mouse model of oxidative stress and neurotoxicity.Methods: An ethanolic extract of S.aromaticum seeds was prepared and the active compounds were identified using nuclear magnetic resonance spectroscopy.BALB/c mice were divided into five groups(negative control, AlCl_3-treated, self-recovery, AlCl_3 + S.aromaticum, S.aromaticum only; n=10) and treated with AlCl_3 and S.aromaticum extract.Expression of oxidative markers [Superoxide dismutase 1(SOD1) and peroxiredoxin 6(Prdx6)] and amyloid precursor protein(APP) in the hippocampus and cortex was evaluated via PCR.Histopathological assessment was performed to investigate the extent of neurodegeneration.Results: It was observed that AlCl_3 exposure increased the expression of APP770 while simultaneously down regulated the expression of APP695.AlCl_3 also induced a significant decrease(P0.05) and an increase(P0.05) in the expression level of SOD1 and Prdx6, respectively.A substantial decrease substantial(P0.05) in the density of Nissl substance was also observed in cortex of the mice treated with AlCl_3.Interestingly, treatment with S.aromaticum extract normalized the alterations in the expression level of SOD1, Prdx6 and APPisoforms and improved the neuronal structural damage.Conclusions: The results showed that S.aromaticum is a promising antioxidant and a neuroprotective agent.     

Replicative senescence of human dermal fibroblasts affects structural and functional aspects of the Golgi apparatus

It is well recognized that the world population is ageing rapidly. Therefore, it is important to understand ageing processes at the cellular and molecular levels to predict the onset of age‐related diseases and prevent them. Recent research has focused on the identification of ageing biomarkers, including those associated with the properties of the Golgi apparatus. In this context, Golgi‐mediated glycosylation of proteins has been well characterized. Additionally, other studies show that the secretion of many compounds, including pro‐inflammatory cytokines and extracellular matrix–degrading enzymes, is modified during ageing, resulting in physical and functional skin degradation. Since the Golgi apparatus is a central organelle of the secretory pathway, we investigated its structural organization in senescent primary human dermal fibroblasts using confocal and electron microscopy. In addition, we monitored the expression of Golgi‐related genes in the same cells. Our data showed a marked alteration in the Golgi morphology during replicative senescence. In contrast to its small and compact structure in non‐senescent cells, the Golgi apparatus exhibited a large and expanded morphology in senescent fibroblasts. Our data also demonstrated that the expression of many genes related to Golgi structural integrity and function was significantly modified in senescent cells, suggesting a relationship between Golgi apparatus function and ageing.     

Insight into the molecular pathophysiology of myelodysplastic syndromes: targets for novel therapy

Myelodysplastic syndromes (MDS) are clonal hematopoietic stem cell disorders characterized by abnormal cellular differentiation and maturation with variable progression to acute leukemia. Over the last decade, scientific discoveries have unraveled specific pathways involved in the complex pathophysiology of MDS. Prominent examples include aberrations in cytokines and their signaling pathways (such as tumor necrosis factor‐alpha, interferon‐gamma, SMAD proteins), mutations in genes encoding the RNA splicing machinery (SF3B1, SRSF2, ZRSR2, and U2AF1 genes), mutations in genes disrupting the epigenetic machinery (TET2, DNMT3A, DNMT3B, EZH2, ASXL1). In addition, abnormalities in regulatory T‐cell dynamics and atypical interactions between the bone marrow microenvironment, stroma and progenitor cells, and abnormal maintenance of telomeres are also notable contributors to the complex pathogenesis of MDS. These pathways represent potential targets for novel therapies. Specific therapies include drugs targeting aberrant DNA methylation and chromatin remodeling, modulating/activating the immune system to enhance tumor‐specific cellular immune responses and reduce anomalous cytokine signaling, and blocking abnormal interaction between hematopoietic progenitors and stromal cells.     

Interleukin-4 Modulation of Platelet-Derived Growth Factor–Induced Smooth Muscle Cell Urokinase Plasminogen Activator

Platelet-derived growth factor (PDGF) stimulates smooth muscle cell (SMC) migration owing to stimulation of SMC tissue plasminogen activator (t-PA) production. In this study we examined the effects of the T-cell lymphokine interleukin-4 (IL-4) on PDGF induction of human aortic SMC antigen levels of urokinase-type plasminogen activator (u-PA) and those of plasminogen activator inhibitor-1 (PAI-1), the endogenous inhibitor of t-PA and u-PA, measured by enzyme-linked immunosorbent assays (ELISAs). u-PA antigen levels from human aortic SMC incubated with PDGF 100 ng/mL and IL-4 500 U/mL were significantly greater than those incubated with PDGF 100 ng/mL alone. Coincubation of PDGF with IL-4 did not significantly increase SMC u-PA antigen levels in cellular lysates. Coincubation with PDGF 100 ng/mL and IL-4 500 U/mL did not significantly affect SMC PAI-1 antigen levels in conditioned media or cellular lysates. Therefore, interleukin-4 modulates vascular SMC u-PA production induced by PDGF.