A method of noise removal using the inverse transform of an image autocorrelation function

A method for a reversible transform between an image and image autocorrelation function has been devised, and it has been applied to the reduction of random noise in a microscope image. Object-related features of an image signal as well as noise features are overlapped at the vicinity of the origin of an image autocorrelation, and a peak is formed at this position. The present method removes the noise contribution in this peak and returns the autocorrelation function, thus corrected, to the image. An autocorrelation function is computed by two Fourier transforms as based on the convolution theorem. The inverse transform from the image autocorrelation function is made possible by performing two Fourier transforms in reverse to the above. This method has been developed to remove random noise more accurately from a single image (especially for nonperiodic images) than other image-processing methods such as smoothing techniques and low pass filtering.     

20-[18F]fluoroarachidonic acid: tissue biodistribution and incorporation into phospholipids

The in vivo behavior of 20-[18F]fluoroarachidonic acid (18F-FAA) was investigated to evaluate its potential use as a radiotracer for studying the regional brain and heart lipid metabolism by positron emission tomography (PET). Tissue biodistribution studies in rats have revealed that 18F-FAA has a high uptake in the liver and lung, thus probably reflecting the metabolism, and is accompanied by both low in vivo defluorination and low blood levels. At 30 min postinjection, the uptake in the brain and heart reached values of 0.26 +/- 0.02 and 1.22 +/- 0.58% dose/g, respectively, with ratios to the blood radioactivity of 1.04 and 4.88, respectively. Lipid extraction at 30 min postinjection showed that 39% of the brain radioactivity was in the organic phase whereas the organic phase from heart tissue contained 73% of the total radioactivity. A TLC analysis demonstrated that 18F-FAA was mainly bound to phospholipids in the brain and heart tissue as expected. Based on the findings of this study, the utility of 18F-FAA as an in vivo tracer for cerebral phospholipid studies appears to be limited because of its relatively high radioactivity in the aqueous brain fraction. However, our findings do suggest that this agent might be useful as a tool for studies of cardiac phospholipid turnover, even though it demonstrated a poor heart-to-lung and heart-to-liver contrast.     

Reduction in acquisition time of scanning electron microscopy image using complex hysteresis smoothing

Complex hysteresis smoothing (CHS), which was developed for noise removal of scanning electron microscopy (SEM) images some years ago, is utilized in acquisition of an SEM image. When using CHS together, recording time can be reduced without problems by about one-third under the condition of SEM signal with a comparatively high signal-to-noise ratio (SNR). We do not recognize artificiality in a CHS-filtered image, because it has some advantages, that is, no degradation of resolution, only one easily chosen processing parameter (this parameter can be fixed and used in this study), and no processing artifacts. This originates in the fact that its criterion for distinguishing noise depends simply on the amplitude of the SEM signal. The automation of reduction in acquisition time is not difficult, because CHS successfully works for almost all varieties of SEM images with a fairly high SNR.     

The conversion of a field-emission scanning electron microscope to a high-resolution,high-performance scanning transmission electron microscope,while maintaining original functions

Recently, the reliability of field-emission electron guns has increased. In addition, the cost of computer systems for on-line processing has dropped. Hence, we should now consider the use of scanning transmission electron microscopy (STEM) for routine work, especially, in the field of biology where one may expect to utilize digital image processing techniques. An STEM has been constructed, without disturbing the original functions, by converting a commercial scanning electron microscope equipped with a fieldemission gun. The STEM is generally operated at accelerating voltage 30 kV, focal length 7.5 mm, and beam current 1?2 × 10^?10 A. Several improvements have been incorporated for removing the effects of vibration, contamination, and stray magnetic fields. Also, an adjustable detector aperture was utilized. The modified instrument was connected to an on-line digital image processing system for utilizing the information obtained from STEM images. The advantages of the modified system were studied from various viewpoints.     

An improved scanning method based on characteristics of the human visual system for scanning electron microscopy

An improved scanning method for the scanning electron microscope (SEM) is proposed. Here, quincuncial scanning (sampling) instead of a conventional (raster) scanning is used. This scanning method is very effective for quality improvement of an SEM image obtained under undersampling conditions (rough sampling). The present study focuses on characteristics of the human visual system, specifically the low response of eyes in diagonal directions. When using this method coupled with a high-precision interpolation, the number of pixels necessarily doubles. It is not surprising that it is advantageous for printing. A more important advantage is the fact that SEM images can be acquired with a shorter recording time. Hence, this type of scanning will be helpful for quick and frequent recordings in a "snapshot" mode, which up to now has not been achieved successfully by SEM.     

Crystallographic, thermoelectric, and mechanical properties of polycrystalline type-I Ba8Al16Si30-based clathrates

Crystallographic, thermoelectric, and mechanical properties of polycrystalline Ba₈Al₁₆Si₃₀-based samples with type-I clathrate structure prepared by combining arc melting and spark plasma sintering methods were investigated. The major phase of the samples was a type-I clathrate with an actual Al/Si ratio of ~15/31, strongly suggesting that framework deficiency was absent or was present in very low concentration in the samples. The Hall carrier concentration n of the samples was approximately 1 × 10²¹ cm^?3, which is lower than the values reported so far for the Ba₈Al₁₆Si₃₀ system. Other important material parameters of the samples were as follows: the density-of-states effective mass m* = 2.3m ₀, Hall mobility μ = 7.4 cm² V^?1 s^?1, and the lattice thermal conductivity κ _L = 1.2 W m^?1 K^?1. The thermoelectric figure of merit ZT reached approximately 0.4 (900 K) for a sample with n = 9.7 × 10²⁰ cm^?3. Simulation using the experimentally determined values of material parameters showed that ZT reached values >0.5 if the carrier concentration is optimized at about 3 × 10²⁰ cm^?3. Young’s, shear, and bulk moduli were estimated to be approximately 98, 39, and 117 GPa, respectively, and Poisson’s ratio was found to be 0.25 from the longitudinal and transverse velocities of sound, v _L = 6038 m/s and v _T = 3503 m/s, respectively, for a sample with ZT = 0.4. The coefficient of thermal expansion (CTE) ranged from approximately 8 × 10^?6 K^?1 to 10 × 10^?6 K^?1 (330–690 K), which is smaller than the values reported for Ba₈Ga₁₆Ge₃₀ and Sr₈Ga₁₆Ge₃₀ clathrates.     

MOSFET hot-carrier reliability improvement by forward-body bias

Active threshold voltage V/sub TH/ control via well-substrate biasing can be utilized to satisfy International Roadmap for Semiconductors performance and standby power requirements for CMOS technology beyond the hp65-nm node. In this letter, the impact of substrate bias V/sub SUB/ on hot-carrier reliability is presented. The impact varies with the gate length and body effect factor. These findings are explained, and the effects of future scaling are discussed using a quasi-two-dimensional model. Significant and important improvement in hot-carrier lifetime with forward-bias V/sub SUB/ can be expected for deeply scaled CMOS devices, making it an attractive method for extending the scalability of bulk-Si transistor technology.     

MOSFET design for forward body biasing scheme

Forward body biasing is a solution for continued scaling of bulk-Si CMOS technology. In this letter, the dependence of 30-nm-gate MOSFET performance on body bias is experimentally evaluated for devices with various channel-doping profiles to provide guidance for channel engineering in a forward body-biasing scheme. Furthermore, simulations of 10-nm-gate CMOS (hp22-nm node) devices are performed to study the optimal channel-doping profile and gate work function engineering for a forward biasing scheme.     

Effect of organic amine type on the structure and properties of the complex Zn(II) salts of ethylene–methacrylic acid copolymer with organic amines

The complex Zn(II) salts of ethylene–methacrylic acid copolymer (EMAA) were synthesized by using various organic amines from monoamines to polyamines, from primary amines to tertiary amines, and from molecular amines to polymer amines. Thermal analyses by differential scanning calorimetry (DSC), and the measurement of stiffness, melt flow rate (MFR), and dielectric properties were employed for the complex salts. It was found that the valence, strength of base, rigidity and flexibility, and bulkiness of the organic amines affect the degree of crystalline order of the ionic crystallites, which governs the stiffness of the complex ion ionomers. The stiffness is higher for the complex salts which form the higher orderliness in the ionic aggregates. The organic amines with two or more primary aliphatic amino groups and higher boiling temperatures from more rigid ionic crystallites in the complex ion ionomers leading to the enhanced modulus. Monoamines or polyamines with amino groups attached to flexible chains such as polyether and polysiloxane scarcely develop ionic crystallites and preferentially solvate the amorphous region including ionic groups leading to the decreased modulus. These results provide us with the fundamental information to control the modulus of ionomers.     

Image restoration for TV‐scan moving images acquired through a semiconductor backscattered electron detector

A semiconductor backscattered electron (BSE) detector has become popular in scanning electron microscopy session. However, detectors of semiconductor type have a serious disadvantage on the frequency characteristics. As a result, fast scan (e.g. TV‐scan) BSE image should be blurred remarkably. It is the purpose of this study to restore this degradation by using digital image processing technology. In order to improve it practically, we have to settle several problems, such as noise, undesirable processing artifacts, and ease of use. Image processing techniques in an impromptu manner like a conventional mask processing are unhelpful for this study, because a complicated degradation of output signal affects severely the phase response as well as the amplitude response of our SEM system. Hence, based on the characteristics of an SEM signal obtained from the semiconductor BSE detector, a proper inverse filter in Fourier domain is designed successfully. Finally, the inverse filter is converted to a special convolution mask, which is skillfully designed, and applied for TV‐scan moving BSE images. The improved BSE image is very effective in the work for finding important objects. SCANNING 31: 229–235, 2009. © 2010 Wiley Periodicals, Inc.