A New Three-Component Photo-Initiating System for Visible Light Recording of Volume Holograms with Single-Pulsed Laser

Versatile substituted electron-deficient trichloromethylarenes can easily be synthesized and combined with a Safranine O/triarylalkylborate salt to form a highly efficient three-component photo-initiation system that starts free radical polymerization to finally form holographic gratings with a single-pulsed laser. The mechanism of this photo-initiation most likely relies on an electron transfer from the borate salt into the semi-occupied HOMO of the excited dye molecule Safranine O, which after fragmentation generates an initiating alkyl radical and longer-lived dye radical species. This dye radical is most probably oxidized by the newly introduced trichloromethylarene derivative as an electron acceptor. The two generated radicals from one absorbed photon initiate the photopolymerization and form index gratings in a suitable holographic recording material. This process is purely photonic and does not require further non-photonic post treatments.

Review of Organic Photorefractive Materials and Their Use for Updateable 3D Display

Photorefractive materials are capable of reversibly changing their index of refraction upon illumination. That property allows them to dynamically record holograms, which is a key function for developing an updateable holographic 3D display. The transition from inorganic photorefractive crystals to organic polymers meant that large display screens could be made. However, one essential figure of merit that needed to be worked out first was the sensitivity of the material that enables to record bright images in a short amount of time. In this review article, we describe how polymer engineering was able to overcome the problem of the material sensitivity. We highlight the importance of understanding the energy levels of the different species in order to optimize the efficiency and recording speed. We then discuss different photorefractive compounds and the reason for their particular figures of merit. Finally, we consider the technical choices taken to obtain an updateable 3D display using photorefractive polymer. By leveraging the unique properties of this holographic recording material, full color holograms were demonstrated, as well as refreshing rate of 100 hogels/second.

Tunable Waveguides Couplers Based on HPDLC for See-Through Applications

Photopolymers have become an important recording material for many applications, mainly related to holography. Their flexibility to change the chemical composition together with the optical properties made them a versatile holographic recording material. The introduction of liquid crystal molecules in a photopolymer based on multifunctional monomer provides us the possibility to generate tunable holograms. The switchable holographic elements are a key point for see-through applications. In this work, we optimize the holographic polymer-dispersed liquid crystals composition to improve the performance of tunable waveguide couplers based on transmission gratings and specifically their response under an applied electric field. A variation around 60% in the transmission efficiency was achieved.

Percepções acerca de adolescência por parte de professores de ciências

Resumo: Discutimos percepções sobre adolescência de um grupo de professores de ciências que frequentaram um curso de extensão. Para tanto, realizamos uma pesquisa qualitativa em educação com foco no cotidiano escolar que incluiu como instrumentos de pesquisa: material proveniente de videogravação, produções dos professores e anotações da pesquisadora. Na análise, usamos algumas ideias de Moscovici para representações sociais. Constatamos percepções pouco divergentes em relação aos estereótipos de adolescentes difundidos socialmente, ainda que tenham ocorridos avanços (como o reconhecimento de características dos adolescentes, das referências etc.) em direção aos conceitos científicos trabalhados no curso. Esperamos maior atenção sobre adolescência na formação de professores de ciências, posto que, possivelmente, essas percepções estão presentes na forma com que os professores exercem seu trabalho.Palavras-chave: Adolescência; Ensino de Ciências; Formação Continuada de Professores de Ciências Perceptions about adolescence by science teachersAbstract: We discussed perceptions about adolescence of a Science teachers group who attended an extension course. Although, we conducted a qualitative research in education with a focus on school routine, which included as research tools: video recording material, teachers productions and the researcher`s notes. In this analysis, we used some of Moscovici`s ideas for social representations. We found slightly divergent perceptions in relation to adolescents stereotypes that are socially disseminated. Even though advances have occurred (such as the recognition of adolescents characteristics, references and etc.) towards the scientific concepts worked on that course. We expect greater attention on adolescence in the training of Science teachers, since these perceptions are present in the way that teachers exercise their work.Keywords: Adolescence; Science Teaching; Continuing Education of Science Teachers.

INOVASI MODEL PEMBELAJARAN JARAK JAUH PROGRAM KESETARAAN PAKET C DI MASA PANDEMI COVID-19

Pandemi COVID-19 telah menghambat proses belajar dan pembelajaran baik pendidikan formal maupun pendidikan non formal seperti pada program kesetaraan Paket C. Guru atau tutor dituntut untuk dapat menghadirkan inovasi pembelajaran yang efektif. Pembelajaran jarak jauh dapat menjadi salah satu alternatif yang dapat diterapkan. Artikel ini bertujuan untuk mendeskripsikan inovasi model pembelajaran jarak jauh pada Program Kesetaraan di wilayah Purwokerto Selatan pada masa pandemik COVID-19. Jenis penelitian ini adalah penelitian kualitatif dengan metode etnografi. Pengumpulan data menggunakan tiga teknik yakni; melakukan observasi, wawancara, dan studi dokumen. Setelah data diperoleh kemudian peneliti melakukan analisis, adapun teknik analisis yang digunakan yakni; mereduksi, analisis dan penarikan kesimpulan. Hasil penelitian ini menunjukkan bahwa terdapat tiga metode pembelajaran yakni daring (live book, kuis, recording materi), luring (proyek karya), dan kombinasi (group observation or self-observation, rekaman materi, diskusi, investigasi dan webinar, dan apresiasi belajar). Ketiga metode pembelajaran ini merupakan modifikasi sekaligus adaptasi pembelajaran jarak jauh di masa pandemi COVID-19.The COVID-19 pandemic has hampered the learning and its process at all levels of education ranging from early childhood education to college. In addition to formal education, non-formal education such as the Package C Equality Program has also undergone drastic changes in the teaching and learning process. From that problem teachers or tutors are required to be able to present effective learning innovations. Distance learning can be one of the applicable alternatives. This article aims to describe the innovation of distance learning models in the Equality Program in the South Purwokerto region during the COVID-19 pandemic. This study is a field research with a qualitative approach. Data was collected using three techniques, namely; observations, interviews and document studies. The data then analysed based on these steps; reduction, analysis and withdrawal of conclusions. The results of this study show that there are three methods of learning namely online (live book, quiz, recording material), offline (project work), and combination (group observation or self-observation, recording material, discussion, investigation and webinar, and appreciation of learning). These three learning methods are both modifications and adaptations of distance learning during the COVID-19 pandemic.

A Review of Polarization-Sensitive Materials for Polarization Holography

Polarization holography has the unique capacity to record and retrieve the amplitude, phase, and polarization of light simultaneously in a polarization-sensitive recording material and has attracted widespread attention. Polarization holography is a noteworthy technology with potential applications in the fields of high-capacity data storage, polarization-controlled optical elements, and other related fields. The choice of its high-performance materials is particularly important. To further develop polarization holography applications and improve the quality of the information recorded (i.e., material sensitivity and resolution), a deeper understanding of such materials is needed. We present an overview of the polarization-sensitive materials, which introduced polarization holographic technology and the development of polarization holographic materials. The three main types of polarization holographic materials are described, including azopolymer materials, photopolymer material, and photorefractive polymer material. We examine the key contributions of each work and present many of the suggestions that have been made to improve the different polarization-sensitive photopolymer materials.

Effect of Heating Temperature on Magnetic Properties of Fe3O4 Synthesized by Coprecipitation Method

The synthesis of Fe3O4 nanoparticles with iron rock raw materials was carried out using a coprecipitation method. Iron rocks were taken from the Surian village, South Solok of West Sumatera. This research was conducted to utilize local materials and produce low cost, varied magnetic materials to be applied to the electric and electronics industries. Iron sand as a base material was obtained by processing the iron rocks through destruction and extraction. Iron sand that has been extracted is reacted with HCL and NH4OH. Furthermore, the PEG-2000 were added as a template to homogenize and inhibit the growth of particles. Heating temperature variation performed to see the effect of temperature on the magnetic properties of the particles. Heating temperature variations were used at 500 ̊C, 600 ̊C, and 700 ̊C. Phase composition of the samples were confirm using X-ray diffraction method. Characterization of magnetic properties carried out using Vibrating Sample Magnetometer (VSM). The results of magnetic properties show that the saturation magnetization decreases with increasing heating temperature in the range of 32.6883 emu/g, 20,1632 emu/g, and 10.4734 emu/g respectively. The value of coercive force, HC obtained in the range of 13,840 A/m – 19,120 A/m. The results show that Fe3O4 can be used as a magnetic recording material.

Повышение эффективности полимерного нанокомпозита для формирования фотонных структур методом оптической записи

In this work, the conditions for optimizing an optical recording material based on photosensitive acrylate-urethane nanocomposites with silicon oxide nanoparticles, for efficient Bragg gratings recording by multibeam interference method is presented. It was shown that the choice of the most effective monomers and their concentrations in the nanocomposite which depends on their structure and polymerization rate, followed by determination of the optimal recording radiation intensity for the given composition, makes it possible to adjust the conditions for component diffusion and redistribution, and hence, the formation of regions with different refractive indices in the recording medium. These results can be useful for creating complex 2D and 3D photonic structures based on the targeted modification of photosensitive polymer nanocomposites with different properties (luminescent, nonlinear optical, etc.).

SPEAKER’S BEHAVIOR IN VIRTUAL REALITY (Methodology of the Experiment and Description of Preliminary Results)

The article is a preliminary research that examines the methodology of the experiment devoted to the study of the speaker’s behavior in virtual reality (VR) and its results. The purpose of the experiment is to study the specific features of verbal and non-verbal implementation of the role and spatial deixis in VR. Based on the received reactions, the speaker’s coordinate system will be determined and models of the speaker’s communicative behavior in VR will be constructed. The article describes in detail the design of the experiment, which includes: stimulus material on the basis of which the VR scene is created; types of scenes used to determine the type of the speaker’s orientation; description of the tools by means of which VR is created; requirements for the selection of participants in the experiment; methods of recording material and the principles of its decoding. Special attention was paid to correlating the ‘external’ (gesture) and ‘internal’ (verbal) behavior of the speakers, to the principles of gesture fixation and their correlation with the subject’s verbal reactions to the presented scene. Based on the data obtained from the subjects, there was developed a classifier where the categories ‘Structure of the situation’, ‘Type of communication’ and ‘Means of communication’ and their subclasses are used. The data are entered into the Semograph information system and are visually presented in the form of a customizable interactive graph by using the SciVi software. At present, the reactions of two informants (a man and a woman) from the general sample have been processed. Based on the analysis of their reactions, preliminary results were obtained, which made it possible to demonstrate approaches to work with the classifier and to trace the representation of verbal and non-verbal means in the reactions of the subjects. Moreover, preliminary results help to determine the type of orientation and communicative behavior of the speaker depending on their personality and the type of scene. Preliminary analysis allows us to refine the principles of material processing, its annotation and entry into the Semograph system as well as working with the classifier.

Implementasi UML Dan Grennfoot Untuk Membangun Aplikasi Pengucapan Bahasa Inggris

One of the materials in the English Language course is listening, namely the skill of hearing the pronunciation of English sentences. Learning listening must use native speaker or recording material so that the pronunciation is heard according to the original. If you use the course participants as a sound source, there is a high probability of mistakes in the pronunciation of words or sentences. Then an application is needed to help with course activities as tutors or native speakers in giving correct English pronunciation. In this research, English Pronunciation Application was built using the Greenfoot Application with the object oriented programming concept. This application is to help pronoun learning that can output audio when the object clicked. The development method uses SDLC, application modeling uses UML and testing using Black-box testing. The English pronunciation application is compiled into a .jar file so that it can be run on a computer with a Windows operating system that has JDK installed. The test results show that this English learning application can replace tutors, produce the right audio, and can replace native speakers. This can be seen from the results of the questionnaire showing 82%.