Studies on the equatorial spot of G-type contact binary UV Lyn

New CCD photometric observations of G-type contact binary UV Lyn were obtained in 2006 and 2020, when the light curves (LCs) show positive O'Connell effect and negative O'Connell effect, especially. From the previous studies, the LCs by other ground-based telescope are variable from 1973 to 2020, particularly the magnitude difference between the two maxima. These phenomena indicate that the component is active in the past 47 years. In addition, under the monitoring of the space telescope of Transiting Exoplant Survey Satellite (TESS) from January to March in 2020, we fortunately find the continuous variations of O'Connell effect in every circle for the first time. The analysis also shows that in a short time, the positive O'Connell effect has been transformed into the negative one, which proves that there are stronger magnetic activities on the surface of the component. By using the Wilson-Devinney code with a spot model, these photometric solutions confirm UV Lyn is a shallow W-subtype contact binary with a cool equatorial spot on the less massive component. The successive variability of O'Connell effect possibly result from one equatorial cool spot shifting gradually along with time. We also investigate its \emph{O-C} curve from these continuous LCs, there is not obvious variation in such short time. while, the O’Connell effect as the indicator of the magnetic activity are possibly undergoing a periodic trend of a period of nearly 38 days. Comparing \emph{O-C} curve, we could find there is not relation between the period variation and magnetic activity.

Electronic Sensing Platform (ESP) Based on Open-Gate Junction Field-Effect Transistor (OG-JFET) for Life Science Applications: Design, Modeling and Experimental Results

This paper presents a new field-effect sensor called open-gate junction gate field-effect transistor (OG-JFET) for biosensing applications. The OG-JFET consists of a p-type channel on top of an n-type layer in which the p-type serves as the sensing conductive layer between two ohmic contacted sources and drain electrodes. The structure is novel as it is based on a junction field-effect transistor with a subtle difference in that the top gate (n-type contact) has been removed to open the space for introducing the biomaterial and solution. The channel can be controlled through a back gate, enabling the sensor’s operation without a bulky electrode inside the solution. In this research, in order to demonstrate the sensor’s functionality for chemical and biosensing, we tested OG-JFET with varying pH solutions, cell adhesion (human oral neutrophils), human exhalation, and DNA molecules. Moreover, the sensor was simulated with COMSOL Multiphysics to gain insight into the sensor operation and its ion-sensitive capability. The complete simulation procedures and the physics of pH modeling is presented here, being numerically solved in COMSOL Multiphysics software. The outcome of the current study puts forward OG-JFET as a new platform for biosensing applications.

Surface characterization of paper products via a stylus-type contact method

Surface properties include both surface roughness and friction. With a stylus-type contact method, it is necessary to obtain either a surface roughness profile or a friction profile that is affected by stylus shape and size, its contact force on the sample, the scan speed, and the data acquisition rate. As a new surface parameter, the mean absolute deviation (MAD) from an average property has been introduced. It represents the deviation from either the roughness average (Ra) and the average coefficient of friction (COF), respectively. While Ra or average COF depends on the instrument and its operating conditions, the MAD should not depend on them because it represents the variations within the sample.

Preparation and characterization of multifunctional sponge-gourd fibers (Luffa cylindrica)/ hydroxyapatite composites for removal of lead and methylene blue

Cellulose, oxidized-fibers, and oxidized-nanocellulose were isolated from sponge-gourd fibers (Luffa cylindrica). Isolated materials showed different morphology (shape and size), chemical, crystalline properties, and removal efficiency against methylene blue (MB) and lead ions (Pb2+). The cellulosic materials showed high efficiency in removing MB more than Pb2+. So, different luffa forms/hydroxyapatite (HAp) composites were prepared and used as adsorbents for removal of both MB and Pb2+ from aqueous solutions. The effect of sorbent type, contact time, and initial MB and Pb2+ concentrations were studied. HAp was successfully synthesized on the surface of luffa with an average length of 40–56 nm and width of 14–19 nm. Kinetic and adsorption studies of MB and Pb2+ ions were well fitted with the pseudo-second-order model and Langmuir model. The maximum adsorption capacity of MB was 25.2 mg/g, 30.8 mg/g, and 36.2 mg/g for oxidized-fibers/HAp, oxidized-fibers, and cellulose, respectively, and for Pb2+ was 625 mg/g, 714 mg/g, and 714.5 mg/g for oxidized-fibers/HAp, oxidized-nanocellulose/HAp, and cellulose/HAp, respectively. Also, more than 85% of MB (25 mg/L) and 95% of lead (500 mg/L) were removed within the first 5 min. Oxidize-fibers/HAp composite showed effective adsorption with both MB and Pb2+ in a very short time.

Study on detection of lumps in a soft object by using a scanning roller type palpation sensor system

In this study, a palpation sensor system is developed to detect a lump in a soft object. The developed sensor system consists of a contact part using a bearing, two linear sliders and a 3-axis load cell. While the roller type contact part is scanned against a soft object, reaction force applied to the contact part is measured. Lumps are detected by measuring fluctuation of the reaction force. In experiments, the sensor system is scanned against the samples. From the results, it is found that the lump with a small diameter embedded at a deep position.

Vertical Integration of Nitride Laser Diodes and Light Emitting Diodes by Tunnel Junctions

We demonstrate the applications of tunnel junctions (TJs) for new concepts of monolithic nitride-based multicolor light emitting diode (LED) and laser diode (LD) stacks. The presented structures were grown by plasma-assisted molecular beam epitaxy (PAMBE) on GaN bulk crystals. We demonstrate a stack of four LDs operated at pulse mode with emission wavelength of 453 nm. The output power of 1.1 W and high slope efficiency of 2.3 W/A is achieved for devices without dielectric mirrors. Atomically flat surface after the epitaxy of four LD stack and low dislocation density is measured as a result of proper TJ design with optimized doping level. The strain compensation design with InGaN waveguides and AlGaN claddings is shown to be crucial to avoid cracking and lattice relaxation of the 5 µm thick structure. Vertical connection of n-LDs allows for cascade emission of photons and increases the quantum efficiency n-times. The two-color (blue and green) LEDs are demonstrated. Application of TJs simplifies device processing, reducing the need for applications of p-type contact. The key factor enabling demonstration of such devices is hydrogen-free PAMBE technology, in which activation of buried p-type layers is not necessary.