Monitoring of multiple fabrication parameters of electrospun polymer fibers using mueller matrix analysis

Electrospun polymer fiber mats feature versatile applications in tissue engineering, drug delivery, water treatment and chemical processes. The orientation of fibers within these mats is a crucial factor that significantly influences their properties and performance. However, the analysis of fiber samples using scanning electron microscopy (SEM) has limitations such as time consumption, fixed assembly, and restricted field of vision. Therefore, a fast and reliable method for qualitative measurements of fiber orientation is required. Mueller matrix polarimetry, a well-established method for measuring orientation of chemical and biological species, was employed in this case. We investigated the effect of four important parameters of the electrospinning process, namely collector speed, applied voltage, needle-to-collector distance, and solution concentration, on fiber orientation using Mueller matrix polarimetry thus extending the range of parameters analyzed. Measurements were performed using two extreme values and a central optimized value for each fabrication parameter. Changes in matrix values were observed for each fabrication parameter, and their correlation with fiber orientation was analyzed based on the Lu-Chipman decomposition. The results were compared with SEM images, which served as the ground truth, and showed overall good agreement. In the future, the analysis of electrospun polymer fibers can be done by using Mueller matrix polarimetry as alternative to current technology and fabrication parameters, including solution concentration for the first time in this context and the production can quickly be adjusted based on the outcome of the measurements

Investigation of the molecular switching process between spin crossover states of triazole complexes as basis for optical sensing applications

With the advent of the first laser sources and suitable detectors, optical sensor applications immediately also came into focus. During the last decades, a huge variety of optical sensor concepts were developed, yet the forecast for the future application potential appears even larger. In this context, the development of new sensor probes at different scales down to the atomic or molecular level open new avenues for research and development. We investigated an iron based triazole molecular spin-crossover complex changing its absorption characteristics significantly by varying environmental parameters such as humidity, temperature, magnetic or electric field, respectively, with respect to its suitability for a new class of versatile molecular sensor probes. Hereby, besides the investigation of synthesized pure bulk material using different analyzing methods, we also studied amorphous micro particles which were applied in or onto optical waveguide structures. We found that significant changes of the reflection spectra can also be obtained after combining the particles with different types of optical waveguides.The obtained results demonstrate the suitability of the material complex for a broad field of future sensor applications

Thin films with implemented molecular switches for the application in polymer-based optical waveguides

Complexes like iron (II)-triazoles exhibit spin crossover behavior at ambient temperature and are often considered for possible application. In previous studies, we implemented complexes of this type into polymer nanofibers and first polymer-based optical waveguide sensor systems. In our current study, we synthesized complexes of this type, implemented them into polymers and obtained composites through drop casting and doctor blading. We present that a certain combination of polymer and complex can lead to composites with high potential for optical devices. For this purpose, we used two different complexes [Fe(atrz)3](2ns)2 and [Fe(atrz)3]Cl1.5(BF4)0.5 with different polymers for each composite. We show through transmission measurements and UV/VIS spectroscopy that the optical properties of these composite materials can reversibly change due to the spin crossover effect

Spurious transcription causing innate immune responses is prevented by 5-hydroxymethylcytosine

Generation of functional transcripts requires transcriptional initiation at regular start sites, avoiding production of aberrant and potentially hazardous aberrant RNAs. The mechanisms maintaining transcriptional fidelity and the impact of spurious transcripts on cellular physiology and organ function have not been fully elucidated. Here we show that TET3, which successively oxidizes 5-methylcytosine to 5-hydroxymethylcytosine (5hmC) and other derivatives, prevents aberrant intragenic entry of RNA polymerase II pSer5 into highly expressed genes of airway smooth muscle cells, assuring faithful transcriptional initiation at canonical start sites. Loss of TET3-dependent 5hmC production in SMCs results in accumulation of spurious transcripts, which stimulate the endosomal nucleic-acid-sensing TLR7/8 signaling pathway, thereby provoking massive inflammation and airway remodeling resembling human bronchial asthma. Furthermore, we found that 5hmC levels are substantially lower in human asthma airways compared with control samples. Suppression of spurious transcription might be important to prevent chronic inflammation in asthma

Discutindo a educação ambiental no cotidiano escolar: desenvolvimento de projetos na escola formação inicial e continuada de professores

A presente pesquisa buscou discutir como a Educação Ambiental (EA) vem sendo trabalhada, no Ensino Fundamental e como os docentes desta escola compreendem e vem inserindo a EA no cotidiano escolar., em uma escola estadual do município de Tangará da Serra/MT, Brasil. Para tanto, realizou-se entrevistas com os professores que fazem parte de um projeto interdisciplinar de EA na escola pesquisada. Verificou-se que o projeto da escola não vem conseguindo alcançar os objetivos propostos por: desconhecimento do mesmo, pelos professores; formação deficiente dos professores, não entendimento da EA como processo de ensino-aprendizagem, falta de recursos didáticos, planejamento inadequado das atividades. A partir dessa constatação, procurou-se debater a impossibilidade de tratar do tema fora do trabalho interdisciplinar, bem como, e principalmente, a importância de um estudo mais aprofundado de EA, vinculando teoria e prática, tanto na formação docente, como em projetos escolares, a fim de fugir do tradicional vínculo “EA e ecologia, lixo e horta”.Facultad de Humanidades y Ciencias de la Educació

Moderate High Power 1 to 20 µs and kHz Ho:YAG Thin Disk Laser Pulses for Laser Lithotripsy

An AOM or self-oscillation pulsed thin disk Ho:YAG laser system at 2.1 µm with an average power in the 10 W range will be presented for laser lithotripsy. For the gain switched mode of operation a modulated Tm-fiber laser is used to produce self-oscillation pulses between 5 to 20 µs at mJ pulse energies that are available for a local heating of the stone material with a decomposition of the crystalline structure into calcium carbonate powder. Imploding water vapor bubbles between the fiber end and the stone material produce sporadic shock waves which help clear out the stone dust material

2 µm Ho:YAG Thin Disk Laser

A Thulium fiber laser pumped Ho:YAG thin disk laser with 15W (cw) or several mJ (pulsed) operation will be presented. Additionally, a narrow (<0.5nm), tunable (30nm) cw operation near 2.09 µm, will be shown

Injection Seeding a Q-Switched Ho:YAG Laser based on a Self-Organizing Technique for Doppler Wind LIDAR

We report on a Q-switched 2.1 µm Ho:YAG injection-seeded laser system based on a self-organizing technique for Doppler wind LIDAR of up to 10 W average power with a minimal amount of control components

2 µm Ho-YAG and Cr:ZnSe Thin Disk cw Lasers

A Thulium fiber laser pumped Ho:YAG thin disk cw laser with an output power of 15 W at a 2% Ho in YAG concentration and 7 W at 1.6% as well as a Thulium fiber laser pumped Cr:ZnSe thin disk cw laser with an output power of 0.4 W will be presented. Comparison of the output power to a Rigrod formula with Boltzmann occupation factors will be shown