A Pressure Sensing Device to Assist in Colonoscopic Procedures to Prevent Perforation-A Case Study.

Colonoscopy has a limited field of view because it relies solely on a small camera attached to the end of the scope and a screen displayed on a monitor. Consequently, the quality and safety of diagnosis and treatment depend on the experience and skills of the gastroenterologist. When a novice attempts to insert the colonoscope during the procedure, excessive pressure can sometimes be applied to the colon wall. This pressure can cause a medical accident known as colonic perforation, which the physician should prevent. We propose an assisting device that senses the pressure applied to the colon wall, analyzes the risk of perforation, and warns the physician in real time. Flexible pressure sensors are attached to the surface of the colonoscope shaft. These sensors measure pressure signals during a colonoscopy procedure. A simple signal processor is used to collect and process the pressure signals. In the experiment, a colonoscope equipped with the proposed device was inserted into a simulated colon made from a colon extracted from a pig. The processed data were visually communicated to the gastroenterologist via displays and light-emitting diodes (LEDs). The device helps the physician continuously monitor and prevent excessive pressure on the colon wall. In this experiment, the device appropriately generated and delivered warnings to help the physicians prevent colonic perforation. In the future, the device is to be improved, and more experiments will be performed in live swine models or humans to confirm its efficacy and safety.

Mechanism for Local-Atomic Structure Changes in Chalcogenide-based Threshold-Switching Devices.

Threshold-switching devices based on amorphous chalcogenides are considered for use as selector devices in 3D crossbar memories. However, the fundamental understanding of amorphous chalcogenide is hindered owing to the complexity of the local structures and difficulties in the trap analysis of multinary compounds. Furthermore, after threshold switching, the local structures gradually evolve to more stable energy states owing to the unstable homopolar bonds. Herein, based on trap analysis, DFT simulations, and operando XPS analysis, it is determined that the threshold switching mechanism is deeply related to the charged state of Se-Se homopolar defects. A threshold switching device is demonstrated with an excellent performance through the modification of the local structure via the addition of alloying elements and investigating the time-dependent trap evolution. The results concerning the trap dynamics of local atomic structures in threshold switching phenomena may be used to improve the design of amorphous chalcogenides.

Ultrasonic fatigue analysis of 3D-printed carbon fiber reinforced plastic.

The development of 3D printing technologies using composite materials has revolutionized additive manufacturing. Using these technologies, various products can be fabricated with strengths beyond the limits of the strength of the polymer used. However, although parts manufactured using carbon fiber reinforced plastic (CFRP) 3D printing have excellent characteristics, research on their durability is lacking, making their application difficult in the real industry. In this study, an ultrasonic fatigue test was conducted on a CFRP material manufactured by 3D printing to evaluate fatigue performance. Because of the characteristics of CFRP, the strength varies depending on the orientation angle of the carbon fiber, and the durability also varies. Therefore, an experiment on three types of specimens mixed in the bi-direction and uni-direction of 0° and 90° was conducted. For the ultrasonic fatigue test, a specimen design with a special shape is required according to the resonance frequency and dynamic modulus of the material. To this end, a specimen was designed based on measurements of the physical properties of the material according to the angle of the fiber, which were verified by Finite element method (FEM) modal analysis, and the fatigue life was estimated through an actual experiment. The fatigue failure life was simulated by FEM fatigue analysis considering the measured fatigue test results and the derived anisotropic properties simultaneously. Additionally, based on the advantages of CFRP 3D printing, which adjusts the fiber pattern, we fabricated a specimen with a concentric pattern to derive the fatigue life and calculate the actual life improvement. Based on the results of this study, the specific rigidity of the CFRP parts can be optimized by adjusting the fiber pattern. Additionally, the results of this study can aid in the analysis of the fatigue characteristics of 3D-printed CFRP materials.

Synthesis of Fe metal precipitated colloidal silica and its application to W chemical mechanical polishing (CMP) slurry.

The objective of this paper is to develop a new method of Fe (metal) precipitation on colloidal silica to overcome the stability problem, which would be responsible in producing defects, with commercially available fumed silica slurry containing Fe ions. The slurry was developed by using sodium silicate (Na(2)SiO(3)) as a raw material and the concentration of precipitation of metal was controlled by addition of Fe salt (Fe(NO(3))(3)). To compare the concentration of precipitated Fe with directly added Fe ions in slurry solutions, static electrochemical and peroxide decomposition experiments were performed. Although the performance of the Fe precipitation appeared to be lower than Fe ion addition during these experiments, nearly equal removal rate was observed due to the dynamic condition during polishing. The Fe precipitated colloidal silica particles at the concentration of 52ppm showed the similar W removal rate and selectivity of W to TEOS (tetraethylorthosilicate) to commercially available fumed silica slurry containing externally added Fe ions. The introduction of Fe particle precipitation on colloidal silica particles would result in a longer shelf life time and hence lower defect level in W CMP.

Evaluation of Air Samplers for Recovery of Biological Aerosols in Dairy Processing Plants.

An All Glass Impinger-30 (AGI-30), Andersen 6-stage Sieve Air Sampler (Andersen impactor), Reuter centrifugal air sampler (RCS sampler), and the Millipore open type membrane filter sampler (Filter sampler) were evaluated for viable particle recovery in three dairy processing plant environments. There were two size distribution peaks for viable particles, at stage 1 (>7.0 µm) and stage 3 (3.3-4.7 µm). About 10-12% of the particles were smaller than 2.1 µm in size and were mostly non-molds. During milk processing, the highest number of particles were >7.0 µm in size. But, during ice cream processing and in the idle ice cream room, the highest number of particles were 3.3-4.7 µm in size and were mostly molds. Mean viable particle recovery decreased in the order of AGI-30, Andersen impactor, RCS sampler, and Filter sampler for each of the three sampling environments. These results contrast to those obtained using laboratory-generated aerosols where both the AGI-30 and RCS sampler exhibited low recovery. The increased aerosol recovery by AGI-30 in processing plant compared to laboratory-generated aerosols indicates the presence of carrier and passenger type aerosol particles which disintegrate upon impingement. A comparison of the percent of non-mold cfu recovered by the RCS sampler vs. Andersen impactor indicates that the RCS sampler has a bias toward the detection of non-mold containing particles at all three of the locations tested. The Andersen impactor proved to be the most reliable sampler for recovering biological aerosols from dairy processing plant air.

Evaluation of Air Samplers for Recovery of Artificially Generated Aerosols of Pure Cultures in a Controlled Environment.

All Glass Impinger-30 (AGI-30), Andersen 6-stage Sieve Air Sampler (Andersen impactor), Reuter centrifugal air sampler (RCS sampler), and Millipore open type membrane filter sampler (Filter sampler) were evaluated for recovery of artificially-generated aerosols of pure cultures of Pseudomonas fluorescens , Escherichia coli , Streptococcus faecalis , and endospores of Bacillus subtilis . Size distribution of the aerosol was analyzed to determine its relationship to air sampler efficiency. Five min after the spray, 71 to 85% of particles were between 1.1-3.3 µm in size and 3.5 to 10.4% were smaller than 1.1 µm in size. The Andersen impactor recovered significantly greater numbers of nonsporeforming bacteria, with least variability of recovery and the RCS sampler recovered significantly smaller numbers and exhibited greatest variability of the four samplers tested. AGI-30 and Filter sampler performance varied depending on the species tested. For recovery of bacterial endospore, the Filter and Andersen samplers both recovered greater numbers than the AGI-30 and RCS sampler. The RCS sampler recovered a significantly lower number of spores with the most variable results of the four samplers. Our data indicate that the Andersen impactor is the sampler of choice for recovering microbial aerosols of interest to the food processing industry.

Comparison of Airborne Microflora Collected by the Andersen Sieve Sampler and RCS Sampler in a Dairy Processing Plant.

The performance of a Reuter centrifugal air sampler (RCS sampler) was compared with that of an Andersen 6-stage sieve sampler (Andersen impactor) to determine the suitability of the RCS sampler for monitoring airborne microflora in dairy processing plant environments. The types of microorganisms recovered from non-mold colony forming particles using the Andersen impactor and the RCS sampler were different at each location and trial. When selected Gram positive cocci and Gram negative rods were classified using Staph track and API 20E System, respectively, results indicated that the type of bacteria collected using each sampler was similar, though the percentage distributions were different. In addition, bacterial types were not consistently associated with different size particles. The RCS sampler was able to recover most bacterial types since these types were distributed over various particle sizes. When airborne fungi were collected, the RCS sampler recovered significantly lower amounts than that of Andersen impactor. The RCS sampler is suitable for use when approximate concentration of non-mold airborne particles, or relative degree of air cleanliness information is needed.

Biological Aerosols: A Review of Airborne Contamination and its Measurement in Dairy Processing Plants.

Processing plant air is a source of post-pasteurization contamination of dairy products. Little is known about the extent to which biological aerosols contaminate pasteurized products, however evidence indicates that air within a packaging area is a critical control point for both pathogens and spoilage microorganisms. Consequently, it is important to understand the characteristics of biological aerosols, learn how to control their occurrence, and discover practical and valid monitoring methods. Methods used for monitoring viable particles in air include the use of sedimentation plates, impingers, slit and sieve impactors, filters, and centrifugal samplers. Each of these methods has limitations on its usefulness for dairy plant air monitoring. Microorganisms are often injured due to the stresses of the aerosolized state and consequently may not grow on selective media. Sampling methods such as impingement and filtration which subject the organisms to additional stress may cause sufficient injury to prevent growth on non-selective media. However, gentler collection methods such as centrifugal samplers may not generate enough force to collect the smallest viable particles. Aerosols are generated within the dairy plant by worker activity, sink and floor drains, water spraying, and air conditioning systems. Environmental sanitation, air filtration, air flow control, and control over personnel cleanliness and activity are useful control measures. The adoption of "clean room" design principles for a packaging area will aid in controlling biological aerosols in new dairy processing plants.