Scanning Probe Image Processor Research Articles

Influence of HF concentration and current density on characteristic morphological features of mesoporous silicon

This report explores the variations in morphological features of electrochemically fabricated mesoporous silicon as a function of two important fabrication parameters, HF concentration and current density. Four set of samples corresponding to four different HF concentrations (15%, 25%, 35% and 45% HF) were prepared with systematically varied current density (10, 20, 30, 60 and 100 mA/cm2). The effect of these parameters on many significant features like mean pore diameter, mean neighbor distance, pore count per unit area, surface roughness, surface area etc. of resulting mesoporous structure have been determined by very sophisticated UHV SPM (Omicron VT AFM XA) in contact mode. The analysis has been performed using Scanning Probe Image Processor (SPIP Version 6.0.9). The AFM analysis is supported by the results of FESEM JSM 7600F and DXR Raman Microscope. The comparative study shows that some features are more sensitive to HF concentration while others seem to depend more on current density. Pore diameter varies mainly with HF concentration while pore depth varies largely with current density. Exceptionally high pore count (450pores/100 nm2) is found at 45% HF while samples have higher average roughness (3.5 nm) at 15% HF. Sponge like layer is formed at lower current density while well aligned very straight channels are formed at higher current density. Some very interesting regimes found at high current density conditions, recorded by FESEM have also been discussed to develop more understanding of porous silicon formation mechanism.

A morphology-based method for the diagnosis of red blood cells parasitized by Plasmodium malariae and Plasmodium ovale

The morphology of red blood cells (RBCs) is altered significantly during the maturation stages of malaria parasites, which include ring, trophozoite, and schizont. There is dissimilarity in terms of the morphological characteristics of parasitized RBCs infected by the 4 species of Plasmodium, including falciparum, vivax, malariae, and ovale. This makes the process of diagnosis very difficult, which may lead to a wrong treatment method and substantial damage to the health of the patient. An innovative technique in introduced that accurately defines the shape of parasitized RBCs at each stage of infection as a potential method of diagnosis. Giemsa-stained thin blood films were prepared using blood samples collected from healthy donors as well as patients infected with P. malariae and P. ovale. The diameter and thickness of healthy and infected RBCs at each stage of infection were measured from their optical images using Olysia and Scanning Probe Image Processor (SPIP) software, respectively. A shape equation was fitted based on the morphological characteristics of RBCs, and their relative 2-dimensional shapes were plotted using Wolfram Mathematica. At the ring stage, the thicknesses of RBCs parasitized by P. malariae (Pm-RBCs) and P. ovale (Po-RBCs) increased by 42% and 51%, respectively. Both Pm-RBCs and Po-RBCs remained nearly biconcave throughout parasite development even though their volumes increased. It is proposed that the morphology-based characterization technique introduced here could be used to intensify the accuracy of the Giemsa staining diagnosis method for the detection of the Plasmodium genus and infection stage. Based on the significant morphological alterations induced by different Plasmodium species, the results may also find practical use for faster prediction and treatment of human malaria.

Magnetic and topographical modifications of amorphous Co–Fe thin films induced by high energy Ag7+ ion irradiation

We have investigated the effects of swift heavy ion irradiation on thermally evaporated 44nm thick, amorphous Co77Fe23 thin films on silicon substrates using 100MeV Ag7+ ions fluences of 1×1011ions/cm2, 1×1012ions/cm2, 1×1013ions/cm2, and 3×1013ions/cm2. The structural modifications upon swift heavy irradiation were investigated using glancing angle X-ray diffraction. The surface morphological evolution of thin film with irradiation was studied using Atomic Force Microscopy. Power spectral density analysis was used to correlate the roughness variation with structural modifications investigated using X-ray diffraction. Magnetic measurements were carried out using vibrating sample magnetometry and the observed variation in coercivity of the irradiated films is explained on the basis of stress relaxation. Magnetic force microscopy images are subjected to analysis using the scanning probe image processor software. These results are in agreement with the results obtained using vibrating sample magnetometry. The magnetic and structural properties are correlated.

An innovative shape equation to quantify the morphological characteristics of parasitized red blood cells by Plasmodium falciparum and Plasmodium vivax

The morphology of red blood cells is affected significantly during maturation of malaria parasites, Plasmodium falciparum and Plasmodium vivax. A novel shape equation is presented that defines shape of parasitized red blood cells by P. falciparum (Pf-red blood cells) and P. vivax (Pv-red blood cells) at four stages of infection. The Giemsa-stained thin blood films are prepared using blood samples collected from healthy donors, patients having P. falciparum and P. vivax malaria. The diameter and thickness of healthy red blood cells plus Pf-red blood cells and Pv-red blood cells at each stage of infection are measured from their optical images using Olysia and Scanning Probe Image Processor softwares, respectively. Using diameters and thicknesses of parasitized red blood cells, a shape equation is fitted and relative two-dimensional shapes are plotted using MATHEMATICA. The shape of Pf-red blood cell drastically changes at ring stage as its thickness increases by 82%, while Pv-red blood cell remains biconcave (30% increase in thickness). By trophozoite and subsequent schizont stage, the Pf-red blood cell entirely loses its biconcave shape and becomes near spherical (diameter and thickness of ~8 µm). The Pv-red blood cell remains biconcave throughout the parasite development even though its volume increases. These results could have practical use for faster diagnosis, prediction, and treatment of human malaria and sickle-cell diseases.

A non-contact 3D method to characterize the surface roughness of castings

A non-contact technique using a 3D optical system was used to measure the surface roughness of two selected standard surface roughness comparators used in the foundry industry. Profile and areal analyses were performed using scanning probe image processor (SPIP) software. The results show that the surface quality of the standard comparators was successfully evaluated and it was established that the areal parameters are the most informative for cast components. The results from the surface comparators were compared with the results from a stylus instrument. Sand cast components were also evaluated and the surface roughness parameter (Sa) values were compared with those of the standards. Sa parameter suffices for the evaluation of casting surface texture. The S series comparators showed a better description of the surface of castings after shot blasting than the A series.

Association of the Endosomal Sorting Complex ESCRT-II with the Vps20 Subunit of ESCRT-III Generates a Curvature-sensitive Complex Capable of Nucleating ESCRT-III Filaments

The scission of membranes necessary for vesicle biogenesis and cytokinesis is mediated by cytoplasmic proteins, which include members of the ESCRT (endosomal sorting complex required for transport) machinery. During the formation of intralumenal vesicles that bud into multivesicular endosomes, the ESCRT-II complex initiates polymerization of ESCRT-III subunits essential for membrane fission. However, mechanisms underlying the spatial and temporal regulation of this process remain unclear. Here, we show that purified ESCRT-II binds to the ESCRT-III subunit Vps20 on chemically defined membranes in a curvature-dependent manner. Using a combination of liposome co-flotation assays, fluorescence-based liposome interaction studies, and high-resolution atomic force microscopy, we found that the interaction between ESCRT-II and Vps20 decreases the affinity of ESCRT-II for flat lipid bilayers. We additionally demonstrate that ESCRT-II and Vps20 nucleate flexible filaments of Vps32 that polymerize specifically along highly curved membranes as a single string of monomers. Strikingly, Vps32 filaments are shown to modulate membrane dynamics in vitro, a prerequisite for membrane scission events in cells. We propose that a curvature-dependent assembly pathway provides the spatial regulation of ESCRT-III to fuse juxtaposed bilayers of elevated curvature.

EFFECT OF DICLOFENAC SODIUM ANGIOGENESIS USING CHORIOALLANTOIC MEMBRANE (CAM) ASSAY

Angiogenesis, the formation of new blood vessels, is a hallmark of almost all neoplastic and non-neoplastic degenerative diseases. This process supports normal physiology as well as it contributes in progression of different diseases. Angiogenesis contributes in growth of tumor and progressive arthritis. Inflammatory mediators are involved in cancer induced angiogenic process. Cyclo-oxygenases promote these mediators which help in cell migration and endothelial cell spreading. To explore the role of diclofenac sodium in angiogenesis we have used in vitro Chorioallantoic membrane assay. A novel image probing system SPIP (scanning probe image processor) was utilized for assessment and quantification of structural changes in CAMs. Fourteen parameters of 3D surface roughness were also evaluated for quantification. Application of diclofenac sodium on Chorioallantoic membrane at day six of incubation (0.7% concentration of diclofenac sodium) showed anti-angiogenic effect. Results showed marked changes in architecture of CAMs, thinning of primary, secondary and tertiary blood vessels, reduction in surface roughness parameters, increase in kurtosis of surface, and decrease in Abbott curve. The substantial quantities of diclofenac sodium use locally may exhibit anti-angiogenic activity in the same manner those seen in in-vitro and explain its clinical efficacy.

A NOVEL IMAGE PROBING SYSTEM (SPIP) FOR THE ASSESSMENT AND QUANTIFICATION OF STRUCTURAL CHANGES IN CHORIOALLANTOIC MEMBRANE (CAM) CAUSED BY THE STRAWBERRY JUICE

The anticancer potential of berries has been related, at least in part, to a multitude of bioactive phytochemicals. Anticancer effects of berry bioactive are partially mediated through their abilities to counteract, reduce, and also repair damage resulting from oxidative stress and inflammation. To explore the role of angiogenesis we used SPIP (scanning probe image processor) for quantification of results. 0.7% concentration of strawberry juice showed a marked anti-angiogenic effect. There was decrease in diameter of primary, secondary, tertiary blood vessels and decrease in roughness parameters.

Molecular Composition of IMP1 Ribonucleoprotein Granules

Localized mRNAs are transported to sites of local protein synthesis in large ribonucleoprotein (RNP) granules, but their molecular composition is incompletely understood. Insulin-like growth factor II mRNA-binding protein (IMP) zip code-binding proteins participate in mRNA localization, and in motile cells IMP-containing granules are dispersed around the nucleus and in cellular protrusions. We isolated the IMP1-containing RNP granules and found that they represent a unique RNP entity distinct from neuronal hStaufen and/or fragile X mental retardation protein granules, processing bodies, and stress granules. Granules were 100-300 nm in diameter and consisted of IMPs, 40 S ribosomal subunits, shuttling heterologous nuclear RNPs, poly(A)-binding proteins, and mRNAs. Moreover granules contained CBP80 and factors belonging to the exon junction complex and lacked eIF4E, eIF4G, and 60 S ribosomal subunits, indicating that embodied mRNAs are not translated. Granules embodied mRNAs corresponding to about 3% of the human embryonic kidney 293 mRNA transcriptome. Messenger RNAs encoding proteins participating in the secretory pathway and endoplasmic reticulum-associated quality control, as well as ubiquitin-dependent metabolism, were enriched in the granules, reinforcing the concept of RNP granules as post-transcriptional operons.

Influence of data analysis and other factors on the short-term stability of vertical scanning-probe microscope calibration measurements

We report a study of a fundamental limit to the accuracy of vertical measurements made using scanning-probe microscopes (SPM): the short-term stability of a vertical calibration using a waffle-pattern artifact. To test the instrumental component of this stability, we acquired three data series, at different humidity levels. We compare the variations in waffle-pattern depth in these three data series with the differences in depth estimates using several different analysis methods. The three methods tested are: a histogram method, the scanning-probe image processor, and the polynomial step-function fit. To clarify the importance of the analysis method, a discussion of the different leveling, averaging, and depth-estimation aspects of the various methods is presented. To understand the true repeatability limit of SPM calibration, it is necessary to treat imaging artifacts such as tilt, nonlinearities, and image bow carefully. We find that, when such care is taken, the dependence of the average waffle-cell depth on algorithm is around 0.1%. This is less than the standard deviation of the step-height estimates of around 0.5%, which may be attributed to short-term instrumental variations in vertical SPM calibration. This is a far better stability than the 5%–10% variations observed under long-term aging of the piezo scanner. However, the histogram algorithm, which does not correct image bow, gives an average waffle-cell depth estimate which is nearly 1% higher than the others, indicating that careful image analysis is necessary if the measurement accuracy is to be comparable to the short-term stability of the piezo scanner.