Optical Performance of Single Point-Focus Fresnel Lens Concentrator System for Multiple Multi-Junction Solar Cells—A Numerical Study

This paper investigates the potential of a new integrated solar concentrated photovoltaic (CPV) system that uses a solo point focus Fresnel lens for multiple multi-junction solar cells (MJSCs). The proposed system comprises of an FL concentrator as the primary optical element, a multi-leg homogeniser as the secondary optical element (SOE), a plano-concave lens, and four MJSCs. A three-dimensional model of this system was developed using the ray tracing method to predict the influence of aperture width, height, and position with respect to MJSCs of different reflective and refractive SOE on the overall optical efficiency of the system and the irradiance uniformity achieved on the MJSCs’ surfaces. The results show that the refractive homogeniser using N-BK7 glass can achieve higher optical efficiency (79%) compared to the reflective homogeniser (57.5%). In addition, the peak to average ratio of illumination at MJSCs for the reflective homogeniser ranges from 1.07 to 1.14, while for the refractive homogeniser, it ranges from 1.06 to 1.34, causing minimum effects on the electrical performance of the MJSCs. The novelty of this paper is the development of a high concentration CPV system that integrates multiple MJSCs with a uniform distribution of rays, unlike the conventional CPV systems that utilise a single concentrator onto a single MJSC. The optical efficiency of the CPV system was also examined using both the types of homogeniser (reflective and refractive).

Preclinical study to improve microbubble-mediated drug delivery in cancer using an ultrasonic probe with an interchangeable acoustic lens

Focused ultrasound with microbubbles (FUS-MBs) has shown that it can lead to an efficient drug delivery system (DDS) involving the oscillation and destruction of the MB but is limited in drug delivery due to its narrow pressure field. However, unfocused ultrasound with MBs (UUS-MBs) and an interchangeable acoustic lens can tune and enhance the pressure field for MB destruction to overcome the disadvantages of FUS-MB DDSs. We designed a lens suitable for an ultrasound-phased array probe and studied the optimal treatment conditions for MB destruction in vitro through an optical imaging setup. The DDS effects were evaluated in a rat hepatoma model using doxorubicin (DOX) treatment. A concave lens with a radius of curvature of 2.6 mm and a thickness of 4 mm was selected and fabricated. UUS-MBs with the acoustic lens at 60 Vpp for 32 cycles and a PRF of 1 kHz could induce MB destruction, promoting the DDS even under fluidic conditions. In the animal experiment, the UUS-MBs in the acoustic lens treatment group had a higher concentration of DOX in the tumor than the control group. Our system suggests uses an acoustic lens to increase DDS effectiveness by providing sufficient ultrasound irradiation to the MBs.

Description of Science Process Skills of Physics Education Students of Jambi University on Refraction Material on Concave Lenses Using E-Module

Purpose of study: This study was conducted to determine the science process skills of physics education students for refraction material on a concave lens. The questions discussed in this study are to describe the basic and integrated science process skills of Jambi University physics education students, what are the obstacles faced when the implementation of the e-module basic physics practicum II is applied, what are the solutions to the obstacles faced. Methodology: This study uses a quantitative approach with descriptive methods. This research was conducted in the Physics Education Laboratory of the Teacher Training and Education Faculty, Jambi University. The sample l in this study were 40 physics education students contracting basic physics II subjects. The sampling technique used in this study was a total sampling technique. Main findings: With the use of a Manual for Basic Physics 1 practicum in the form of e-module, it can improve students' science process skills. It can be seen from the research results, that the science process skills of physics education students at Jambi University on refraction practicum material on concave lenses Novelty/Originality of this study: With this research, students are motivated to improve science process skills so that they become more active and more familiar with the concept of learning and can improve learning outcomes. Through this research, students can become more innovative and creative teachers, and can also find out the extent of students' science process skills.

PREVALENCE AND PATTERN OF REFRACTIVE ERRORS: A CROSS SECTIONAL STUDY AT TERTIARY HEALTH CENTER

Refractive error is the most common ocular morbidity worldwide. Throughout the world the main causes of visual impairment are uncorrected refractive errors 43% followed by cataract 33% and glaucoma in 3 % cases. Children being unaware of their problem do not complain about it. Untreated refractive error can lead to amblyopia and poor school performance which in long run can lead to considerable impact on child’s future. A Hospital based cross sectional observational study was conducted in the ophthalmology department of NMCH, Patna, Bihar. Total 612 children of age group 5 to 16 years coming to the OPD were enrolled in the study. Myopia is the most common refractive error in childhood. It is corrected by using concave lens. Other types of refractive errors are hypermetropia and astigmatism. Uncorrected refractive errors among children have considerable impact on their learning & academic achievements. So, screening is the only way for early detection of refractive errors. Early diagnosis and treatment will prevent onset of amblyopia & visual disability.

Miniaturized Ultrasound Transducer Composed of a Composite of Multiple Piezoelectric Stacks

This paper aims to develop a miniaturized ultrasound transducer for intravascular thrombolysis, which requires a transducer with high mechanical index (> 0.3) and a long focal distance (> 2.0 mm). To meet this need, a composite of a multi-pillar piezo stack (MPPS) transducer was designed and fabricated by using PZT-4, conductive epoxy, soft elastomer, and a metallic concave lens. The simulation results showed the predominant extensional mode at around 0.92 MHz. The −6 dB focal distance was elongated by 150% from that of the common single-pillar piezo stack (SPPS) transducer with the same aperture. The acoustic pressure was improved by 8.2 dB at the focal zone. Next, the experimental results showed the peak-to-negative pressure of 1.92 MPa under 120 Vpp input, which was sufficient to cause the inertial cavitation of microbubble contrast agents. The −6 dB focal distance reached up to 3.4 mm which was a significant improvement compared to the conventional SPPS transducer. The developed intravascular transducer will be employed for the microbubble-mediated ultrasound thrombolysis to reduce the treatment time.

Development of a Rapid Manufacturing Process for Concave and Convex Lens Arrays

This paper reports a rapid manufacturing process for the production of concave and convex lens arrays on the polymer substrate. In this method, many small steel balls with highly polished surfaces were placed in a rectangular cavity to form a closely packed small steel ball array. Then, a polymer substrate (PMMA sheet) was placed on top of the small steel ball array, and the stack of the PMMA sheet and the small steel ball array was placed in a hot embossing machine. During the hot embossing process operation, a concave lens array pattern is directly fabricated onto a polymer substrate. In addition, the diameter and depth of the concave lens array can be changed and controlled by adjusting the processing conditions of the hot embossing process. Thus, concave lens arrays with different dimension can be fabricated. Next, the polymer substrate with concave lens array pattern can be used as a mold for rapid replication of polymer convex lens array using vacuum-assisted UV molding process. In this way, various concave and convex lens arrays can be rapid fabricated with high throughput and low cost.