bluuebunny/crossref_metadata_2025_split huggingface dataset:
Direct assessment of recombination noise in semiconductors using electron beam‐induced conductivity
Authors: Mil'shtein S. 
Published: June 2010

AbstractThe level of internal noise of the transistors, diodes, and other semiconductor components limits the successful design of any low noise electronic system. All types of noise, namely, Johnson, 1/f, and so forth, are generated due to activity of crystalline defects such as vacancies, dislocations, and others. The intensity of the electron scattering and recombination processes, inflicted by defects (traps), controls the level of noise. Dependent on the dynamic operation condition of semiconductor devices, such as external biases and level of current injection, the traps will generate certain type and level of noise. Material growth or device processing technologies could introduce all kind of defects. Therefore, characterization of the semiconductor wafer in the early stages of processing (at least before packaging) could help to predict the level of noise due to the type and density of defects present on the wafer. Sorting out bad semiconductor chips could save money and effort in the radio frequency design of low‐noise circuits. This current study focuses on 1/f noise modeling, which involves most powerful generators of noise and linear defects, named dislocations. The study also examines the possibility of assessing this noise by quantitative electron beam‐induced conductivity (EBIC) measurements. These defects could be found in the bulk as well as at the epitaxial interfaces of a semiconductor device. The nanoscale size of these defects makes the scanning electron beam an instrument of choice for the proposed study. Conventional EBIC produces images of the defects, where contrast is proportional to the recombination rate at the site of a defect. Since contrast is measured as a fraction of one percent, the relative nature of contract value precludes quantitative measurements of the recombination rate, thus making quantitative assessment of 1/f noise impossible. In our model, using the Boltzman continuity equation, the recombination‐generation processes per unit of length of a dislocation was defined for two operational conditions of EBIC, namely, for low and high intensity of an electron beam. The experimental technique of the quantitative measurement of carrier recombination (Mil'shtein 2001) consists of taking two EBIC scans along the selected defect at two different beam intensities, digitally subtracting the first scan from the second one and normalizing the result to the size of the electron range. The value of the recombination rate, extracted from the model, could then be used to predict the level of 1/f noise in the tested semiconductor sample.
Investigation of unusual inactivity of industrial platinum‐rhodium catalyst gauze
Authors: Lomic Gizela , Kis Erne , Marinkovic‐Neducin Radmila , Grabovac Marijana 
Published: June 2010

AbstractThe aim of this work was to obtain information about the causes of unusual lack of activation of fresh, unused, 90% platinum‐10% rhodium catalyst gauze that was detected after the activation process in an industrial ammonia oxidation plant. To reach the usual efficiency, it was necessary to regenerate the catalyst immediately after the activation procedure by using an acid bath. To avoid future unexpected shutdowns in the ammonia oxidation plant, the possible sources of impurities accumulated on the catalyst surface were investigated by an analysis of the experimental results and technological processes. The absence of accumulation on the unused catalyst surface eliminates the possibility of contamination during the preparation, while the composition of the impurities indicates that it cannot result from the reactor construction material. In mixed feedstock, detectable amounts of the poisons mentioned were not detected either after filtration or before the reactor. All these considerations imply that the time when the catalyst contamination occurred must have been before the contact with the gas mixture. From data obtained, it is hypothesized that the origin of this substance is from the polluted air in the industrial area where the ammonia oxidation plant is located and that the accumulation probably took place during the preparation of the catalyst pad.
Scanning tunneling microscope spectroscopy of polymers
Authors: Zypman Fredy R. 
Published: June 2010

AbstractThis paper presents theoretical results on the relationship between density of states (DOS) and scanning tunneling microscope current‐voltage curves in polymers. We considered samples of linear hydrocarbons electrically grounded at one of their extremes. The other extreme is electrically connected to the microscope tip via electron tunneling through vacuum. When a voltage, V, is applied to the tip, electric current, I, flows in the tip‐sample circuit. This current varies as the voltage varies and depends on the DOS to the extent that no current would flow if no electron states exist at a certain energy (or voltage). The detailed relationship between DOS and the current‐voltage (I‐V) curve is not known a priori. We solve the corresponding quantum problem in the context of tight binding and find that I‐V reproduces accurately the resonant energy peaks of the DOS. We apply the results to 100 atom‐long alkane and alkene chains and found that there is a significant voltage shift in the corresponding curves as to discriminate one structure from the other.
A prototype two‐detector confocal microscope for in vivo corneal imaging
Authors: Petroll W. Matthew , Jester James V. , Cavanagh H. Dwight , Yu Alex , Li Jie , Black Truman 
Published: June 2010

AbstractConfocal microscopy through‐focusing (CMTF) of the cornea produces a three‐dimensional (3‐D) display of corneal structure and intensity profiles that allow objective measurements of corneal sublayer thickness and relative assessment backscattering of light. In this study, a prototype confocal instrument was evaluated in which a photon counting photomultiplier tube (PMT) detector was added to provide faster and more quantitative measurements, while still maintaining the imaging capability of the microscope. To acquire images and measure backscattered light simultaneously, an uncoated pellicle beam splitter was incorporated into the light path of the confocal microscope. This beam splitter reflects 8% of the confocal signal to the PMT. The CMTF scans were performed on four rabbits using the prototype instrument. Corneal images and 3‐D reconstructions acquired with and without the beam splitter in the light path appeared identical. Both the camera and PMT CMTF curves had easily identifiable peaks corresponding to the epithelium, basal lamina, and endothelium. No significant differences were found between PMT and camera CMTF measurements of epithelial, stromal, or corneal thickness (n=12 scans). Furthermore, a high correlation was found between camera and PMT measurements (linear regression analysis, y =0.999× −0.4, r=0.99, p<0.001). The data suggest that by adding a pellicle beam splitter, CMTF intensity data can be acquired using a PMT. The PMT has a faster sampling rate and greater dynamic range than the camera and provides a count of the photons detected. Thus, the instrument has the potential for improving corneal pachymetry and back‐scattering measurements while still providing high‐resolution corneal images.
A method to measure the effective gas path length in the environmental or variable pressure scanning electron microscope
Authors: Gauvin Raynald , Griffin Brendan , Nockolds Clive , Phillips Matthew , Joy David C. 
Published: June 2010

AbstractA simple method is described to determine the effective gas path length when incident electrons scatter in the gas above the specimen. This method is based on the measurement of a characteristic x‐ray line emitted from a region close to the incident beam. From various experimental measurements performed on various microscopes, it is shown that the effective gas path length may increase with the chamber pressure and that it is also often dependent of the type of x‐ray bullet.
Two‐dimensional simulation and modeling in scanning electron microscope imaging and metrology research
Authors: Postek Michael T. , Vladár András E. , Lowney Jeremiah R. , Keery William J. 
Published: June 2010

AbstractTraditional Monte Carlo modeling of the electron beam‐specimen interactions in a scanning electron microscope (SEM) produces information about electron beam penetration and output signal generation at either a single beam‐landing location, or multiple landing positions. If the multiple landings lie on a line, the results can be graphed in a line scan‐like format. Monte Carlo results formatted as line scans have proven useful in providing one‐dimensional information about the sample (e.g., linewidth). When used this way, this process is called forward line scan modeling. In the present work, the concept of image simulation (or the first step in the inverse modeling of images) is introduced where the forward‐modeled line scan data are carried one step further to construct theoretical two‐dimensional (2‐D) micrographs (i.e., theoretical SEM images) for comparison with similar experimentally obtained micrographs. This provides an ability to mimic and closely match theory and experiment using SEM images. Calculated and/or measured libraries of simulated images can be developed with this technique. The library concept will prove to be very useful in the determination of dimensional and other properties of simple structures, such as integrated circuit parts, where the shape of the features is preferably measured from a single top‐down image or a line scan. This paper presents one approach to the generation of 2‐D simulated images and presents some suggestions as to their application to critical dimension metrology.
Cryostatic micro‐computed tomography imaging of arterial wall perfusion
Authors: Kantor Birgit , Jorgensen Steven M. , Lund Patricia E. , Chmelik Michael S. , Reyes Denise A. , Ritman Erik L. 
Published: June 2010

AbstractA double‐walled copper vessel, 32 cc in volume, was fabricated for scanning tissue specimens while maintained below freezing point. To keep specimen temperature within ±1°C, temperature sensors within the chamber control, the rate of inflow of the cold nitrogen gas vented through the chamber. The specimen is attached to a small platform on top of a vertical pin which is attached to the computer‐controlled rotating stage under the vessel. The purpose of this arrangement is to permit scanning of specimens up to 2 cm3 that (1) cannot be “fixed” (e.g., with formalin) because of analyses which are incompatible with prior fixation (certain immunohistochemistry and biomolecular methods), or (2) are “snap”‐frozen during a transient process, such as the accumulation and/or washout of radiopaque indicators. Examples of “cryoscans” of porcine carotid and coronary artery wall opacification in either untouched or acutely stented arteries, snap‐frozen immediately after selective intra‐arterial injection of a contrast agent, show accumulation of contrast in the extravascular space indicating increased endothelial permeability or endothelial and medial disruption following stent placement. The detection of contrast in the adventitia suggest that vasa vasorum deliver the contrast agent from the main lumen to the adventitial extravascular space but not to the media.
A method for personal expertise‐independent evaluation of image resolution in scanning electron microscopy
Authors: Ishitani Tohru , Sato Mitsugu 
Published: June 2010

AbstractThe two conventional methods currently employed for the evaluation of image resolution in scanning electron microscopy are the gap method and a fast Fourier transform (FFT) method. These can be highly dependent on personal expertise on the distinction between signal information and noise contained in a micrograph. Hence, the present paper proposes an alternative method (referred to as a contrast‐to‐gradient (CG) method) that can determine the image resolution of a micrograph without requiring personal expertise on the judgment of noise. The image resolution in the CG method is defined as a weighted harmonic mean of the local resolution, which is proportional to the quotient of the threshold contrast divided by the local gradient. The local gradient is calculated from the quadratic function that best fits the local pixel intensities over 5 × 5 pixels. It has been shown that the CG method, compared with the FFT method, has a broader range of applications for various types of images, such as low‐contrast, noise‐containing, filter‐processed, highly directional, and quasi‐periodic feature images.
Determination of a translocation chromosome by atomic force microscopy
Authors: Ergun Mehmet Ali , Karaoguz Meral Yirmibes , Ince Gonul Didem , Menevse Adnan , Tan Erdal 
Published: June 2010

AbstractAtomic force microscopy (AFM) has been used to study the translocation involving chromosomes 11 and 13. An amniocentesis procedure was performed at 18 weeks of pregnancy on a familial balanced translocation carrier mother whose karyotype was 46, XX, t(11;13) (q23;q34). After harvesting the tissue cultures, light microscopy studies (LM) have indicated that the fetus had the same translocation. A 0.3 μm gap region on the derivative chromosome 13 was determined by AFM; it was equivalent to a mid‐sized G‐band. The enhanced resolution of AFM with respect to its line measure analysis and three‐dimensional image capture capability has allowed an extension and reconsideration of conclusions about chromosomal aberrations based on the study of LM preparations. In this manner, chromosomal disorders will be studied at nanoscale to help in the planning of new therapy strategies.
Morphologic variations in bacteria under stress conditions: Near‐ field optical studies
Authors: Cefalì E. , Patanè S. , Arena A. , Saitta G. , Guglielmino S. , Cappello S. , Nicolò M. , Allegrini M. 
Published: June 2010

AbstractThe morphologic and structural variations suffered by cells of a population of Pseudomonas aeruginosa ATCC 27853 under stress conditions were investigated by using scanning near‐field optical microscopy. The analysis of the images, supported by microbiological data, showed that the bacteria evolved from the initial distribution of rod‐shaped cells of standard size to a population with structural and morphologic modifications. The detection of variations in the optical reflectivity over a sub‐wavelength scale (⩽ 100 nm), combined with the concurrently acquired topographical signal, allowed the visualisation of rod‐shaped bacteria going towards a lytic process and entire “U”‐shaped cells. In the latter cells, which derived from a morphology refolding of rod bacteria, cellular matter seemed to rearrange itself to attain a coccoid stress resistant form, responsible for the residual viability of the population.
Confocal Endoscopy via Structured Illumination
Authors: Karadaglić D. , Juškaitis R. , Wilson T. 
Published: June 2010

AbstractWe describe a simple modification to a rigid endoscope so as to provide both high‐quality conventional and confocal images of reasonably accessible regions of the body. This versatile system uses a structured illumination approach together with a conventional incoherent illumination source. Images taken in fluorescence are presented using this combined conventional and confocal endoscope.
Cytochrome Oxidase Activity and Confocal Laser Scanning Microscopic Analysis of the Hamster Submandibular Gland Using Microwave Irradiated Fixation
Authors: Moriguchi K. , Utsumi M. , Maeda H. , Kameyama Y. , Ohno N. 
Published: June 2010

AbstractSubmandibular glands of the hamster were irradiated in 2% paraformaldehyde (pFA)‐0.5% pure glutaraldehyde (PGA) with a microwave (MW) processor at temperatures of 10° and 37°C. Electron microscopy showed that cytochrome oxidase activity was taking place in the mitochondrial intermembrane‐intracristal space of the granular duct cell when the temperature of the MW‐irradiated fixatives was at 10°C. However, a decrease of this activity was observed when we took care to keep the temperature of the MW‐irradiated fixatives at 37°C. The distinct reduction of cytochrome oxidase activity allowed by MW irradiation seems to be due the thermal affects of fixatives. Of course, the possibility cannot be excluded that MW irradiation caused other undetectable membrane damage. Then, we used confocal laser scanning microscopy for the preservation check of the mitochondrial membrane for cytochemistry with MW‐irradiated fixation. The fluorescence of rhodamine 123 was observed in the inner spaces of the mitochondria at temperatures of 10° and 37°C. When the same tissues were fixed with 2% pFA using an MW processor as the sole fixative at 10°C, no mitochondrial fluorescence was observed. Cytochrome oxidase activity, by contrast, could be seen in the mitochondrial intermembrane‐intracristal spaces in the same condition. Formaldehyde is not the best aldehyde for the purpose of ultra‐structural preservation. On the other hand, light and electron microscopy showed that the endogenous peroxidase activity was localized in the nuclear envelope, endoplasmic reticulum, secretory granules, and Golgi apparatus of the hamster submandibular gland using 2% pFA‐0.5% PGA fixative with and without MW irradiations at temperatures of 10° and 37°C. Some of the same cells were fixed with only 2% pFA under MW irradiation at 10°C; however, marked diffuseness of the peroxidase activity was observed. Therefore, these results indicated that cytochrome oxidase activity was sensitive to heat with MW‐irradiated fixation. Peroxidase activity was very resistant to heat with MW‐irradiated fixation but not with pFA solo fixation, therefore, PGA had to be used.
Combined atomic force microscopy and scanning tunneling microscopy imaging of cross‐sectioned GaN light‐emitting diodes
Authors: Bender J. W. , Salmon M. E. , Russell P. E. 
Published: June 2010

AbstractCross‐sectional scanning tunneling microscopy (STM) was combined with atomic force microscopy (AFM) over the same area to characterize a cross‐sectioned GaN light emitting diode. Because GaN is typically grown on a non‐native substrate and also forms a wurtzite crystal structure, a cryogenic cleaving technique was developed to generate smooth surfaces. The depletion region surrounding the p‐n junction was clearly identified using STM. Furthermore, by imaging under multiple sample biases, distinctions between the n‐doped and p‐doped GaN could be made.
Spectra and lifetimes of fluorescence resonance energy transfer fluorophores under two‐photon excitation
Authors: Ashman Ross , Gu Min , Crimeen‐Irwin Blessing , Ludford‐Menting Mandy , Russell Sarah 
Published: June 2010

AbstractWe show two‐photon spectra and lifetimes acquired using conventional confocal microscopes equipped with an ultra‐short pulsed laser and a time‐gated intensified charge coupled device. We report on the two‐photon spectra and lifetimes of Alexa350, enhanced green fluorescent protein (EGFP), EGFP‐CD46, and Cy3 labelled antibodies. Cellular and extracellular EGFP two‐photon spectra and lifetimes are compared.
Autoschizis of human ovarian carcinoma cells: Scanning electron and light microscopy of a new cell death induced by sodium ascorbate: Menadione treatment
Authors: Gilloteaux J. , Jamison J. M. , Arnold D. , Jarjoura D. , von Greuningen V. , Summers J. L. 
Published: June 2010

AbstractHuman ovarian carcinoma (MDAH 2774) cells were treated with sodium ascorbate (VC), menadione (VK3), or a combination of both in a ratio 100:1 for 1 h and then examined with scanning electron microscopy (SEM) and light microscopy (LM). Light microscopy data corroborated SEM observations, which demonstrated that death of VC + VK3‐treated tumor cells occurred primarily by autoschizis. This type of cell death is characterized by a decrease in cell size, cytoplasmic self‐excisions, and nuclear and nucleolar morphologic degradations without the formation of apoptotic bodies. Ultimately, cell death results from karyorrhexis and karyolysis. This study illustrates that plasma membrane damage (branching filopodia, blisters, blebs) results from VC treatment; cytoskeletal damage and self‐morsellation are caused by VC, VK3, and VC+VK3 treatments. The VC treatment results in a 23% decrease in cell diameter while VK3‐treated cells decrease cell diameter by 66%. After 1 h of VC+VK3 treatment, a heterogenous cell population is found. This population can be resolved into one population whose diameters are 23% smaller than those of sham‐treated cells, and a second population whose diameters are approximately twice those of sham‐treated cells. This second population is indicative of doublet formation in which the cells appear to be dividing (an early stage of autoschizic cell death). One half of the doublet contains the cell nucleus while the other half consists of cytoplasm and membrane only. The enucleate portion of this doublet will then be excised. When the types of cell death are enumerated following VC+VK3 treatment 43% of the cells die by autoschizis, 3% by apoptosis, and 1.9% by oncosis. These results confirm that autoschizis is the principal form of cell death that results from the in vitro treatment of human ovarian carcinoma cells with the vitamin combination.
Specimen Charging and Detection of Signal from Non‐conductors in a Cathode Lens‐Equipped Scanning Electron Microscope
Authors: Zobačová J. , Frank L. 
Published: June 2010

AbstractThis paper concerns the problems connected with the observation of a nonconductive specimen in a scanning electron microscope (SEM) when incident electrons create a surface charge and a corresponding electric field. The special configuration of the cathode lens enables one to control the landing energy of primary electrons via the specimen bias. In the cathode lens, the accelerating electric field at the surface of the specimen combines itself with that of the surface charge in influencing the trajectories of the signal electrons and hence the detected signal level and the possible recapturing of slow secondaries. Recaptured electrons reduce the ultimate positive surface potential, which arises when working below the higher critical energy of electron impact. Computer simulations of electron trajectories were performed for the typical cathode lens configuration and for a model specimen characterized by emission yields similar to those for glass. The simulations brought an extensive set of data about the trajectories of both secondary and backscattered electrons. Furthermore, the data were processed in order to assess the charge balance between the emitted and recaptured electrons as well as the collection efficiency of the detector. The results include values of the ultimate positive surface potential and the detected signal level, both in dependence on the initial energy of the electron impact and the size of the field of view. Finally, the method for the determination of critical energy is reevaluated. This is based on the measurement of the time dependence of the detected signal.