Analysis Students' Misconception in Optical Material Using Three Tier Multiple Choice Diagnostic Test

This study aims to analyze the misconceptions of Senior High School students and their cause in Optical material. The data collection techniques used in this research are tests and interviews. The three tiers multiple-choice diagnostic test used consists of three levels, the first is a question, the second is the reason for the answer, and the third is the student's confidence level. The data analysis techniques used in this research are multiple-choice scoring analysis without fining and student's misconceptions level's percentage analysis. The lowest misconception level is 10.4% on the light refraction indicator, and the highest is 41.6% on the distance and characteristic of the image on the concave mirror. The sources of students' misconceptions found in this study are the students themselves, books, friends, teachers, students' daily experiences, and the Internet.

Corneal Lymphangiogenesis: Current Pathophysiological Understandings and Its Functional Role in Ocular Surface Disease

The cornea is a transparent and avascular tissue that plays a central role in light refraction and provides a physical barrier to the external environment. Corneal avascularity is a unique histological feature that distinguishes it from the other parts of the body. Functionally, corneal immune privilege critically relies on corneal avascularity. Corneal lymphangiogenesis is now recognized as a general pathological feature in many pathologies, including dry eye disease (DED), corneal allograft rejection, ocular allergy, bacterial and viral keratitis, and transient corneal edema. Currently, sizable data from clinical and basic research have accumulated on the pathogenesis and functional role of ocular lymphangiogenesis. However, because of the invisibility of lymphatic vessels, ocular lymphangiogenesis has not been studied as much as hemangiogenesis. We reviewed the basic mechanisms of lymphangiogenesis and summarized recent advances in the pathogenesis of ocular lymphangiogenesis, focusing on corneal allograft rejection and DED. In addition, we discuss future directions for lymphangiogenesis research.

Wound healing of the corneal epithelium: a review

The corneal epithelium (CE) forms the outermost layer of the cornea. Despite its thickness of only 50 μm, the CE plays a key role as an initial barrier against any insults to the eye and contributes to the light refraction onto the retina required for clear vision. In the event of an injury, the cornea is equipped with many strategies contributing to competent wound healing, including angiogenic and immune privileges, and mechanotransduction. Various factors, including growth factors, keratin, cytokines, integrins, crystallins, basement membrane, and gap junction proteins are involved in CE wound healing and serve as markers in the healing process. Studies of CE wound healing are advancing rapidly in tandem with the rise of corneal bioengineering, which employs limbal epithelial stem cells as the primary source of cells utilizing various types of biomaterials as substrates.

EXPLORING THE EFFECTS ON FIFTH GRADERS’ CONCEPT ACHIEVEMENT AND SCIENTIFIC EPISTEMOLOGICAL BELIEFS: APPLYING THE PREDICTION-OBSERVATION-EXPLANATION INQUIRY-BASED LEARNING MODEL IN SCIENCE EDUCATION

The inquiry-based learning model can facilitate students’ understanding of scientific concepts. Scientific epistemological beliefs (SEBs) are related to students’ beliefs about the nature of the process of knowledge in science education. However, whether the “prediction-observation-explanation” (POE) inquiry-based learning model can facilitate fifth graders’ concept achievement and SEBs in science education has not been extensively studied. This study selected the unit of Light Refraction to explore the effects of POE learning on fifth graders’ science concept achievement and SEBs. The Light Refraction Test and Scientific Epistemological Beliefs measurement were applied to the two groups prior to and following the experiment. The experimental group (N=86) participated in POE inquiry-based learning, whereas the control group (N=88) participated without POE inquiry-based learning. The results revealed a significant difference between the two groups, with the experimental group learners performing better than the control group in the concept achievement. In addition, the results showed better positive effects of POE on experimental group learners’ SEBs in the scales of Source and Certainty. Findings suggested that learners achieved better concept achievements and SEBs with the approach of POE inquiry-based learning, which pointed to certain implications for inquiry-based teaching, as well as in education of future science instructors. Keywords: inquiry-based learning model, light refraction, prediction-observation-explanation, science education, scientific epistemological beliefs

A Single-Camera Synthetic Schlieren Method for Measuring Two-Dimensional Liquid Surfaces

A single-camera synthetic Schlieren method is introduced here to measure two-dimensional topography and depth of dynamic free liquid surfaces. The method is simple and easy to implement. Because of light refraction (following Snell’s law), markers on a flat bottom which are seen through the surfaces of a transparent liquid are virtually displaced. This leads to a governing equation that the liquid surface depth (and its topography) is associated with the marker displacement. In the equation, the refractive index of the liquid (e.g. water) can be obtained by a refractometer (or from a technical reference), and the displacements of the markers can be obtained by a cross-correlation method which is usually used in particle image velocimetry. In the equation, the only unknown, the depth of the surface, can be obtained by solving the governing equation with boundary conditions. Unlike free-surface synthetic Schlieren (FS-SS) of Moisy et al. (Exp. Fluids, 1021, 46, 2009), our method does not require a reference depth (which is obtained before or after experiments), so that flows with temporally evolving depth can be measured. Experiments of liquid ripples and dam-break flows were performed to test the method. The results agree well with those obtained with FS-SS and visualization measurements.

O que é preciso saber sobre microabrasão

Objective: Having in mind the growing value that is given to esthetic procedures it has been carried out a literature review about the main polemics that goes around Enamel Microabrasion technique. Action mechanism: the microabrasion compound modifies light refraction and reflection indexes producing an optical effect which allows the camouflage of the subsurface stains. Indications: the technique is indicated to remove any stain, since it is restrict to the most superficial layer of enamel. Advantages: immediate and permanent results with minimum loss of dental structure. Technique: with all care steps taken, a mixture of hydrochloric acid or phosphoric acid and pumice is applied to dental surface for 12 to 16 times, during 10 seconds each application. The application can be done manually or with the help of a low rotation hand-piece. Conclusions: the enamel microabrasion is an effective, safe and conservative technique if compared with other alternatives available. However, some authors affirm that it must be very carefully used because of enamel loss and risks of lesion by the acid.

Echolocating bats rely on an innate speed-of-sound reference

Animals must encode fundamental physical relationships in their brains. A heron plunging its head underwater to skewer a fish must correct for light refraction, an archerfish shooting down an insect must “consider” gravity, and an echolocating bat that is attacking prey must account for the speed of sound in order to assess its distance. Do animals learn these relations or are they encoded innately and can they adjust them as adults are all open questions. We addressed this question by shifting the speed of sound and assessing the sensory behavior of a bat species that naturally experiences different speeds of sound. We found that both newborn pups and adults are unable to adjust to this shift, suggesting that the speed of sound is innately encoded in the bat brain. Moreover, our results suggest that bats encode the world in terms of time and do not translate time into distance. Our results shed light on the evolution of innate and flexible sensory perception.

Ultraviolet Luminescence of ZnO Whiskers, Nanowalls, Multipods, and Ceramics as Potential Materials for Fast Scintillators

The presented work is dedicated to the study and comparison of scintillating properties of zinc oxide samples prepared in different morphologies: whiskers, nanowalls, multipods, and ceramics. It was shown that total transmittance, photo- and radioluminescence spectra, and radioluminescence kinetics can vary significantly depending on sample structure and preparation conditions. The highest total transmittance was registered for ZnO ceramics (>50% at 0.5 mm thickness). Differences in the transmittance of whiskers, nanowalls, and multipods can be attributed to their shape and thickness which affects the amount of light refraction and scattering. The study of radioluminescence demonstrated that all samples, except undoped ceramics and air annealed whiskers, have predominantly fast luminescence with a decay time <1 ns. High transmittance of ceramics opens the way for their use in the registration of high energy X-ray and gamma radiation, where a large volume of scintillators is required. In cases, where large scintillator thickness is not a necessity, one may prefer to use other ZnO structures, such as ensembles of whiskers and nanowalls. Studies of near-band-edge luminescence components at low temperatures showed that the structure is quite similar in all samples except Ga doped ceramics.

Scanning probe microscopic study of P(VDF-TrFE) based ferroelectric nanocomposites

Ceramic and polymer based nanocomponents combine the properties of their constituents, e.g. flexibility, elasticity, polymer reprocessability, hardness typical of glass, wear resistance and high light refraction index. This helps improving many properties of the materials in comparison with the source components. Since recently researchers have been manifesting interest to the properties of complex composite compounds. This is primarily caused by the unique properties of their structures as compared with conventional materials having homogeneous composition. Secondly, this interest is caused by the fact that these compounds may prove to be much cheaper than homogeneous structures provided the physical properties of the composite in a preset range of parameters (temperature, applied field frequency etc.) are identical to those of the respective homogeneous materials. For example, polyvinyl idenfluoride (PVDF) type ferroelectric polymers and copolymers on its basis have found wide application for functional elements of various electromechanic devices in advanced electronics due to their relatively good piezoelectric and pyroelectric properties. The strong random polarization and the formation of polar non-centrosymmetric crystals provide for the high piezoelectric and pyroelectric activity in these crystals. Scanning probe microscopy has been used for study of ferroelectric nanocomposites having different compositions. The matrix specimen for study of local polarization switching at a nanoscale level was vinyl idenfluoride and trifluoroethylene P(VDF-TrFE) copolymer possessing sufficiently high crystallinity. The composite fillers were barium titanate BaTiO3 and deuterized triglycinsulfate DTGS ferroelectric powders and zirconate-titanate lead barium BPZT ceramic powder. We show these materials to show good promise for use in memory cells.