Academic literature on the topic 'Optical density (OD)'
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Journal articles on the topic "Optical density (OD)"
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Willey, Ronald R. "Designing Metallic Neutral Density Filters with Constant Optical Density Versus Wavelength." Space Science Journal 1, no. 2 (2024): 01–07. http://dx.doi.org/10.33140/ssj.01.02.08.
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Observations in space and on earth can be subject to wide dynamic ranges of light levels which may need to be controlled by neutral density filters. The optical density (OD) of neutral density (ND) filters made with single metal layers is often not very neutral or constant in OD versus wavelength over the wavelength band of interest. Photographers are the major users of quantities of ND filters, but there are many other applications for smaller numbers of ND filters. There are a limited number of publications on how to design metallic ND filters. It is shown here that designs of metal-dielectric-metal (MDM) can be designed to have more constant OD over a wavelength band. Designs are shown employing software which accommodates the fact that the indices of thin metal films usually vary with film thickness
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Mira, Portia, Pamela Yeh, and Barry G. Hall. "Estimating microbial population data from optical density." PLOS ONE 17, no. 10 (2022): e0276040. http://dx.doi.org/10.1371/journal.pone.0276040.
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The spectrophotometer has been used for decades to measure the density of bacterial populations as the turbidity expressed as optical density–OD. However, the OD alone is an unreliable metric and is only proportionately accurate to cell titers to about an OD of 0.1. The relationship between OD and cell titer depends on the configuration of the spectrophotometer, the length of the light path through the culture, the size of the bacterial cells, and the cell culture density. We demonstrate the importance of plate reader calibration to identify the exact relationship between OD and cells/mL. We use four bacterial genera and two sizes of micro-titer plates (96-well and 384-well) to show that the cell/ml per unit OD depends heavily on the bacterial cell size and plate size. We applied our calibration curve to real growth curve data and conclude the cells/mL–rather than OD–is a metric that can be used to directly compare results across experiments, labs, instruments, and species.
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Fukue, Masaharu, Zbigniew Lechowicz, Yuichi Fujimori, Kentaro Emori, and Catherine N. Mulligan. "Incorporation of Optical Density into the Blending Design for a Biocement Solution." Materials 15, no. 5 (2022): 1951. http://dx.doi.org/10.3390/ma15051951.
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The engineering practices for applying the microbial precipitation of carbonates require a design of the blending biocement solution (BCS). The BCS is usually blended with concentrated strains NO-A10, reaction media, such as urea and CaCl2, and a solvent, i.e., water or seawater. To characterize the BCS, the unknown microbial characteristics, such as the cell viability, are complex factors. Therefore, the optical density (OD) was redefined as Rcv OD*, in which OD* was the tentative OD of the BCS used and Rcv was the conversion rate concerning the cell viability. To determine Rcv values, a standard precipitation curve based on the precipitation rate at 24 h was determined. It was found that the curve was expressed by λ1 OD+ λ2 OD2, in which λ1 and λ2 were 8.46 M and −17.633 M, respectively. With this, the Rcv and OD values of unknown BCS were estimated from the results of precipitation tests using arbitrary OD* values. By extending the testing time, the second order term of OD or OD* was negligible. Accordingly, the precipitation amount is expressed as 8.46 OD, in which the OD can be estimated by precipitation tests using arbitrary OD* values of BCSs. Unless the Ca2+ value is dominant, the optimum blending of BCS can be determined by OD. Thus, it is concluded that the blending design of BCS is achieved using 8.46 OD, or 8.46 Rcv OD*, and the standard precipitation curve was defined in this study.
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Isaieva, H. O., M. M. Mishyna, Y. A. Mozgova, M. O. Gonchar, O. L. Logvinova, and M. A. Basiuk. "Ability of Microorganisms, Causing Respiratory Infections in Children, to Form Biofilms in vitro." Ukraïnsʹkij žurnal medicini, bìologìï ta sportu 6, no. 1 (2021): 177–83. http://dx.doi.org/10.26693/jmbs06.01.177.
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The purpose of the study was to detect ability to form biofilms by microorganisms that cause respiratory tract infections. Materials and methods. The study involved 97 strains of microorganisms. Microorganisms were isolated from children with respiratory tract infections. All strains, isolated from patients, were able to form biofilms. There were 44 strains of S. aureus (from patients with pneumonia – 13 strains, from patients with other respiratory diseases – 31), 34 strains of S. pneumoniae (pneumonia – 27 strains, other respiratory diseases – 7), 13 strains of K. pneumoniae (pneumonia – 6 strains, other respiratory diseases – 7), 6 strains of P. aeruginosa (pneumonia – 5 strains, other respiratory diseases – 1). Children were treated at the pulmonary department and intensive care unit in Kharkiv Regional Children's Clinical Hospital. Results and discussion. The optical density of primary biofilms formed by Gram-positive microorganisms was 1.33±0.24 Units of OD, and their secondary biofilms was 0.32±0.10 Units of OD. In patients with pneumonia optical density of primary biofilms of Gram-positive microorganisms was 1.48±0.21 Units of OD and of secondary biofilms was 0.30±0.08 Units of OD. Optical density of primary biofilms of Gram-positive microorganisms in patients with other respiratory infections was 1.18±0.15 Units of OD, of secondary biofilms was 0.35±0.12 Units of OD. The optical density of primary biofilms formed by Gram-negative microorganisms was 2.01±1.03 Units of OD, optical density of secondary biofilms was 1.06±0.42 Units of OD. In patients with pneumonia optical density of primary biofilms of Gram-negative microorganisms was 2.57±0.87 Units of OD, of secondary biofilms was 1.21±0.50 Units of OD. Optical density of primary biofilms of Gram-negative microorganisms in patients with other respiratory infections was 1.24±0.66 Units of OD, of secondary biofilms was 0.84±0.11 Units of OD. Conclusion. Gram-negative microorganisms in general formed more massive biofilms compared with Gram-positive microorganisms. Among all microorganisms P. aeruginosa formed the thickest primary and secondary biofilms. Strains of P. aeruginosa isolated from patients with pneumonia formed the thickest primary and secondary biofilms. Strains of S. aureus isolated from patients with other respiratory infections formed most massive primary biofilms, strains of K. pneumoniae formed the hardest secondary biofilms in this group
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Liu, Zilong, Yuxiao Li, Yiqin Jiang, et al. "A New Diffuse Optics Emitter for High Visual Diffuse Transmission Density Measurement." Applied Sciences 9, no. 14 (2019): 2774. http://dx.doi.org/10.3390/app9142774.
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In visual diffuse transmission density measurement, it is hard to measure optical density (OD) up to 6.0 because the signal to noise is more than 10E-06. Thus, there are only two methods to find the measurement. One is using a highly sensitive detector with low background noise, and the other is improving the incident light flux with a wide spectrum, including visual scope. A new diffuse optics emitter was designed to realize OD measurements up to 6.0. It uses 235 optical fibers on a hemisphere to collect and feed in the incident flux, then emits this flux by a diffuse opal. Thus, an incident light with a high diffuse coefficient and high incident flux was realized for high OD measurement. This emitter has been used in the new national reference of National Institute of Metrology, China (NIM) for diffuse transmission optical density. According to the measurement result in this reference, the OD can be measured up to 6.6.
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Chena, Chih-Jung, Kuan-An Chenb, and Ray-Kuang Chianga. "12‐3: Materialization of Mid‐Resolution Quantum Dot Color Converters on G2.5 TFT‐LCD Production Line for Micro‐LED Displays." SID Symposium Digest of Technical Papers 55, no. 1 (2024): 128–31. http://dx.doi.org/10.1002/sdtp.17470.
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This study proposes a mass production solution for quantum dot color converter (QDCC) of mid‐resolution micro‐LED displays. Therefore, a gray bank materials and QD photoresist (PR) with high optical density (OD) and low film thickness were developed. The gray bank materials can achieve OD = 1.08 and a reflectivity of over 25% at a thickness of 4 μm. The red QDPR has OD = 1.93 at 3 μm, and the green QDPR has OD = 1.58 at 3.3 μm. Finally, a 125 PPI and 7‐inch QDCC were fabricated using a G2.5 TFT‐LCD production line, and the optimal material formula and process conditions were determined. Optical analysis shows color point uniformity with STD < 1.3%, indicating that this solution can provide excellent in‐plane uniformity.
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Kamaluddin, Muhammad Wafiq, Agus Indra Gunawan, Setiawardhana Setiawardhana, et al. "Algae content estimation utilizing optical density and image processing method." International Journal of Electrical and Computer Engineering (IJECE) 14, no. 6 (2024): 6248. http://dx.doi.org/10.11591/ijece.v14i6.pp6248-6257.
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One of the factors that influence shrimp cultivation is the presence of algae. Precise knowing algae content in the pond is essential for effective management. Most research in the field of algae species carried out by researchers were observing Chlorella Sp. more than the other algae species, with a particular emphasis on substance concentrations. This study proposed non-invasive techniques for quantifying algae abundance, utilizing optical density (OD) and image processing (IP) methods. Three different algae species are frequently found in Indonesia i.e., Chlorella Sp., Thalassiosira Sp., and Skeletonema Sp. are used as sample. Those samples are cultured and prepared in a certain volume with a certain quantity. For experimental and observation purposes, those samples are then diluted into water based on percentage value. The experimental results provided RGB values, which were then used to establish polynomial equations. To verify these equations, two approaches were employed: synthetic image analysis and evaluation using additional data. The mean average error (MAE) was found to be 3.467 for IP method and 3.513 for OD method. It shows that IP method give better result compared to OD method in this study. However, it is very possible that the two methods will complement each other.
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Lin, Hsiu-Li, Chien-Chung Lin, Yi-Jen Lin, et al. "Revisiting with a Relative-Density Calibration Approach the Determination of Growth Rates of Microorganisms by Use of Optical Density Data from Liquid Cultures." Applied and Environmental Microbiology 76, no. 5 (2010): 1683–85. http://dx.doi.org/10.1128/aem.00824-09.
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ABSTRACT To solve the problems of measuring the growth rates of microorganisms from optical density (OD)-growth time plots, we used relative-density (RD) plots. The relationship of OD and RD was built from the diluted grown cultures. This method was satisfactorily applied to study the growth of Escherichia coli and the cyanobacterium Anabaena spiroides.
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Martins, Márcia Valéria, Marcos André dos Santos da Silva, Edmundo Medici Filho, Luiz Cesar de Moraes, Julio Cezar de Melo Castilho, and Rosilene Fernandes da Rocha. "Evaluation of digital optical density of bone repair in rats medicated with ketoprofen." Brazilian Dental Journal 16, no. 3 (2005): 207–12. http://dx.doi.org/10.1590/s0103-64402005000300007.
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The purpose of this study was to evaluate the influence of ketoprofen on bone repair process in tibiae of rats by means of analysis of the digital optical density. Twenty Wistar rats were assigned to two groups: an untreated control group and a group treated with ketoprofen. The experimental procedures comprised the following stages: general anesthesia, preparation of a unicortical bone defect on the left tibia of each rat, medication with ketoprofen and radiographic examination. Digital radiographic images were acquired using Visualix GX-S-HDI™ digital sensor and an x-ray equipment. Radiographs were taken at baseline, 7, 14, 21 and 30 days postoperatively and the optical density (OD) was evaluated using the Vix winTM 1.4 system. The mean values of OD readings were analyzed statistically by ANOVA and Tukey's test with significance level set at á=5%. The control group showed a statistically significant correlation (p=0.001) between time and optical density, while the ketoprofen group exhibited a weak and not statistically significant correlation (p=0.100). The control group presented the smallest OD ratios at days 1 and 7, and the greatest OD ratios at days 14, 21 and 30, with statistically significant difference (p=0.001). There was no significant differences (p=0.100) among the OD ratios in the ketoprofen group, regardless of the evaluation period. The findings of this study suggest that ketoprofen influenced bone repair process because there was an increase in optical density during the first week and delayed new bone formation after the 21st day.
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Setiani, Nur Asni, Erman Tritama, and Annisa Tresnawulansari. "OPTIMASI OPTICAL DENSITY (OD) PADA ISOLASI GENOM Salmonella typhi MENGGUNAKAN GENOMIC DNA PURIFICATION KIT." Jurnal Sains dan Teknologi Farmasi Indonesia 10, no. 1 (2021): 35. http://dx.doi.org/10.58327/jstfi.v10i1.182.
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<p>Demam tifoid merupakan penyakit infeksi sistemik yang disebabkan oleh bakteri <em>Salmonella typhi</em> dan dapat dicegah melalui pemberian vaksin. Isolasi DNA menjadi tahapan penting untuk menghasilkan DNA murni yang menjadi bahan utama pembuatan vaksin tifoid. Penggunaan <em>genomic</em> DNA <em>purification</em> kit dalam proses isolasi dinilai lebih mudah, tetapi tidak spesifik terhadap bakteri tertentu. Penelitian ini bertujuan menentukan nilai <em>Optical density</em> (OD) yang optimum untuk menghasilkan genom murni <em>Salmonella typhi</em> melalui metode <em>genomic</em> DNA <em>purification</em> kit. Kultur <em>Salmonella typhi</em> ditumbuhkan hingga mencapai variasi OD 0,75; 1,5; dan 3. Isolasi genom dilakukan dengan menggunakan Wizard<sup>®</sup> <em>Genomic</em> DNA <em>Purification</em> Kit. Kemurnian dan konsentrasi DNA dianalisis secara kualitatif melalui elektroforesis gel agarosa dan secara kuantitatif menggunakan qubit dan NanoDrop. Elektrogram menunjukkan adanya pita pada ukuran yang sama dengan ketebalan yang berbeda. Hasil uji kemurnian serta konsentrasi berturut-turut pada OD 0,75 sebesar 2,01; 8,59 μg/ml; OD 1,5 sebesar 1,98; 6,75 μg/ml; OD 3 sebesar 2,02; 13,01 μg/ml. Kemurnian genom terbaik dihasilkan oleh OD 1,5.</p>
Dissertations / Theses on the topic "Optical density (OD)"
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Noriega, Esteban Núria. "The Rtg1 and Rtg3 proteins are novel transcription factors regulated by the yeast hog1 mapk upon osmotic stress." Doctoral thesis, Universitat Pompeu Fabra, 2009. http://hdl.handle.net/10803/7158.
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La adaptación de la levadura Saccharomyces cerevisiae a condiciones de alta osmolaridad está mediada por la vía de HOG ((high-osmolarity glycerol). La activación de esta vía induce una serie de respuestas que van a permitir la supervivencia celular en respuesta a estrés. La regulación génica constituye una respuesta clave para dicha supervivencia. Se han descrito cinco factores de transcripción regulados por Hog1 en respuesta a estrés osmótico. Sin embargo, éstos no pueden explicar la totalidad de los genes regulados por la MAPK Hog1. En el presente trabajo describimos cómo el complejo transcripcional formado por las proteínas Rtg1 y Rtg3 regula, a través de la quinasa Hog1, la expresión de un conjunto específico de genes. Hog1 fosforila Rtg1 y Rtg3, aunque ninguna de estas fosforilaciones son esenciales para regulación transcripcional en respuesta a estrés. Este trabajo también muestra cómo la deleción de proteínas RTG provoca osmosensibilidad celular, lo que indica que la integridad de la vía de RTG es esencial para la supervivencia celular frente a un estrés osmótico.<br>In Saccharomyces cerevisiae the adaptation to high osmolarity is mediated by the HOG (high-osmolarity glycerol) pathway, which elicits different cellular responses required for cell survival upon osmostress. Regulation of gene expression is a major adaptative response required for cell survival in response to osmotic stress. At least five transcription factors have been reported to be controlled by the Hog1 MAPK. However, they cannot account for the regulation of all of the genes under the control of the Hog1 MAPK. Here we show that the Rtg1/3 transcriptional complex regulates the expression of specific genes upon osmostress in a Hog1-dependent manner. Hog1 phosphorylates both Rtg1 and Rtg3 proteins. However, none of these phosphorylations are essential for the transcriptional regulation upon osmostress. Here we also show that the deletion of RTG proteins leads to osmosensitivity at high osmolarity, suggesting that the RTG-pathway integrity is essential for cell survival upon stress.
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Vendrell, Arasa Alexandre. "SCF cdc4 regulates msn2 and msn4 dependent gene expression to counteract hog1 induced lethality." Doctoral thesis, Universitat Pompeu Fabra, 2009. http://hdl.handle.net/10803/7153.
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L'activació sostinguda de Hog1 porta a una inhibició del creixement cel·lular. En aquest treball, hem observat que el fenotip de letalitat causat per l'activació sostinguda de Hog1 és parcialment inhibida per la mutació del complexe SCFCDC4. La inhibició de la mort causada per l'activació sostinguda de Hog1 depèn de la via d'extensió de la vida. Quan Hog1 s'activa de manera sostinguda, la mutació al complexe SCFCDC4 fa que augmenti l'expressió gènica depenent de Msn2 i Msn4 que condueix a una sobreexpressió del gen PNC1 i a una hiperactivació de la deacetilassa Sir2. La hiperactivació de Sir2 és capaç d'inhibir la mort causada per l'activació sostinguda de Hog1.<br/> També hem observat que la mort cel·lular causada per l'activació sostinguda de Hog1 és deguda a una inducció d'apoptosi. L'apoptosi induïda per Hog1 és inhibida per la mutació al complexe SCFCDC4. Per tant, la via d'extensió de la vida és capaç de prevenir l'apoptosi a través d'un mecanisme desconegut.<br>Sustained Hog1 activation leads to an inhibition of cell growth. In this work, we have observed that the lethal phenotype caused by sustained Hog1 activation is prevented by SCFCDC4 mutants. The prevention of Hog1-induced cell death by SCFCDC4 mutation depends on the lifespan extension pathway. Upon sustained Hog1 activation, SCFCDC4 mutation increases Msn2 and Msn4 dependent gene expression that leads to a PNC1 overexpression and a Sir2 deacetylase hyperactivation. Then, hyperactivation of Sir2 is able to prevent cell death caused by sustained Hog1 activation.<br/> We have also observed that cell death upon sustained Hog1 activation is due to an induction of apoptosis. The apoptosis induced by Hog1 is decreased by SCFCDC4 mutation. Therefore, lifespan extension pathway is able to prevent apoptosis by an unknown mechanism.
Conference papers on the topic "Optical density (OD)"
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Kaplan, Simon G., Leonard M. Hanssen, Alan L. Migdall, and Glenn Lefever-Button. "Characterization of high-OD ultrathin infrared neutral density filters." In SPIE's International Symposium on Optical Science, Engineering, and Instrumentation, edited by Raju V. Datla and Leonard M. Hanssen. SPIE, 1998. http://dx.doi.org/10.1117/12.326679.
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Jannson, Joanna, Tomasz Jannson, and Peter C. Yeung. "Holographic wavelength-division multiplexers with low cross-coupling." In OSA Annual Meeting. Optica Publishing Group, 1987. http://dx.doi.org/10.1364/oam.1987.thpo33.
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Fiber-optic multichannel wavelength-division multiplexers (WDMs) with extremely low cross-coupling losses (< −60 dB), based on high optical density (OD) holographic filters, are proposed. The basic architecture of multimode holographic WDMs consists of a cascade of high OD Lippmann-Bragg holograms in waveguide geometry. Based on the optical performance of high-efficiency holographic technology1 developed in the near-UV, visible, and near-IR regions, the intrinsic losses per channel can be as small as 0.05 dB. The number of channels in both multiplexing and demultiplexing modes can exceed 10 with channel separation being 10–15 nm. Multichannel WDMs with low intrinsic and cross-coupling losses are particularly desirable in the next-generation fiber-optic local area network applications.
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Ho, P. P., X. Liang, L. Wang, and R. Alfano. "Snake-Light Translucent Phantoms Tomography." In Advances in Optical Imaging and Photon Migration. Optica Publishing Group, 2022. http://dx.doi.org/10.1364/aoipm.1994.trbsdi.122.
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Translucent phantoms hidden in thick Intralipid scattering solutions have been imaged as a function of phantom scattering coefficient and optical density using picosecond time and spatial gated Kerr-Fourier transillumination imaging system. Weakly-absorbing phantoms of 0.25-mm width black/white bars with the opacity difference of OD=0.14 can be distinguished through a 50-mm highly scattering Intralipid solution. For translucent scattering phantoms, such as droplets and phantom cell, less than 5% differential concentration of a 2-mm thick phantom cell can be distinguished from the background medium with the absolute signal difference of 10−10 of the incident illumination intensity.
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Herrmann, W. C., and D. E. Morton. "Thin Film Optical Coating Filter Stability under Different Environmental Conditions." In Optical Interference Coatings. Optica Publishing Group, 1992. http://dx.doi.org/10.1364/oic.1992.otud7.
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Multilayer coatings have a propensity for the absorption of moisture depending on the porosity and/or density of the materials making up the thin film structure1. To some extent the degree of absorption can determine the durability of the coating and definitely affects the optical performance as the absorbed water molecules fill voids in the materials causing an increase in film indices. This effect can show up as a molted or blotchy appearing coating if the absorption is non-uniform, or irregular, over the surface of the coating or it can be a uniform shifting of the edge for multilayer edge filters2. For applications requiring tight transitions between transmission and reflection (beamsplitters) or high OD rejection of narrow visible bands with high photopic throughput (laser eye protection filters) this phenomenon translates to reduced manufacturing tolerance. Experiments were conducted in order to understand the degree of this effect and to determine how to specify moisture stability testing to assure meeting performance levels upon exposure to all anticipated environmental conditions.
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Willey, Ron. "Estimating the Number of Layers Required and Other Properties of Blocker and Dichroic Optical Coatings." In Optical Interference Coatings. Optica Publishing Group, 1995. http://dx.doi.org/10.1364/oic.1995.ma9.
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We previously1 examined the estimations of what could be expected in the design of antireflection coatings. It is generally known that bandpass, LWP, and SWP filters can be made by properly positioning a QWOT stack or stacks to block or reflect the unwanted wavelengths. Thelen2 also discusses "Minus Filters" wherein the block band is in the middle of two passbands, one on each side. It is helpful when working with any of these designs to be able to estimate how many layers will be required to attain the desired reflection/blocking and how wide the blocked band will be. The optical density (OD = 1/ log Transmittance) increases almost linearly with the number of layers in a QWOT stack. The width of the blocking band increases with the ratio of the indices of the high and low index materials in the stack. The relative width of the blocking band is less with higher orders of the reflection band QWOT wavelength. We can use all of these facts to estimate how many pairs of a given material combination will be required to achieve a given result.
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Patscheke, H., and G. Mathieu. "MONITORING OF THE PLATELET ALPHA-GRANULE SECRETION IN THE AGGREGOMETER." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643492.
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If platelets are stimulated to secrete and the aggregation is prevented by EDTA and no stirring, the optical density (OD) decreases as a consequence of secretion (Patscheke et al. Thromb. Res. 33: 314, 1984). The purpose of this study was to determine which secretory compartment causes the change in OD and to analyze the quantitative relationship between decrease in OD and granule discharge. Human washed platelets were stimulated with thrombin and A 23187 in a Lumi-Aggregometer (Chrono-Log) which permitted simultaneous recording of the change in OD and of the ATP release from dense granules. At various time intervals, platelet factor 4 (PF-4), [3H)serotonin (5-HT), 8-N-ace-tylglucosaminidase (NAG) and lactate dehydrogenase (LDH) were determined in the supernatant as parameters of the release from the alpha granules, dense granules, lysosomes and the cytoplasm, respectively. In order to prevent the platelet shape change (increase in OD) from interfering with secretion (decrease in OD), the platelets were pretreated with 0.1 nM PAF 2 min prior to the secretagogue. PAF induced the shape change but no release of platelet constituents. The results show that the decrease in OD closely correlates with the release of PF-4. The fractional effects were identical in concentration-effect and time-effect studies. However, neither the decrease in OD nor the release of PF-4 were correlated with the release of ATP and 5-HT from the dense granules or the lysosomal release of NAG. The release of ATP and 5-HT required significantly higher agonist concentrations than the decrease in OD and the release of PF-4 and even higher concentrations were required for the release of NAG. LDH liberation did not exceed 1 % with 1 U/ml thrombin, indicating the absence of lysis. Thrombin 1 U/ml caused a maximum decrease in OD of 11 % and 40 % release of PF-4. In a patient with gray platelet syndrome, the decrease in OD was absent while the release of 5-HT was normal. These results show that the decrease in OD is due to alpha-granule secretion. The turbidimetric method offers a valuable tool for kinetic measurements of alpha-granule secretion. By using a Lumi-Aggregometer, secretion from alpha and dense granules can be monitored simultaneously. (Supported by the Deutsche Forschungsgemeinschaft, Grant Pa-263).
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Hadler, Joshua. "Concerns of ultrafast lasers and laser protective eyewear: A review." In ILSC 2023: Proceedings of the International Laser Safety Conference. Laser Institute of AmericaLIA, 2023. http://dx.doi.org/10.2351/7.0001462.
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The use of ultrafast lasers in experimental and commercial operations has increased significantly, and the safe use and appropriate PPE for those operations is of considerable importance. Laser protective eyewear, rated by the Optical Density (OD), are typically tested and rated using low radiance, cw sources. These measurement practices differ considerably to the exposure conditions that ultrafast lasers can produce properties of the materials may behave differently. Eighteen laser eyewear filter samples were tested under controlled conditions using a Ti:Sapphire regenerative amplifier with output pulses centered at 800 nm running from 2 Hz to 1 kHz repetition rate. While many samples maintained their integrity under these test conditions, other samples showed signs of irradiance induced failure which reduced their OD, in some cases transmitting 4–5 orders of magnitude higher than expected. This talks summarizes the results of this study originally published in Journal of Laser Applications 30, 042003 (2018); https://doi.org/10.2351/1.5041760.
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Sundararaj, Kathiresan, and Mohan Bangaru. "In Vitro Biocompatibility Study on Stainless Steel 316L After Nano Finishing." In ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-72606.
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In this present study, the nano finishing of stainless steel 316L (SS316L) was obtained by means of magneto rheological abrasive flow finishing (MRAFF) process by varying the amount of current to the electromagnet. The MRAFF process is an advanced machining process in which the metal removal process is effectively controlled by means of the rheological property of the magneto rheological abrasive (MRA) fluid. After the finishing process, the surface roughness profiles and parameter were obtained with the help of Talysurf coherence correlation interferometer (CCI). Stainless steel 316L sample surfaces obtained by means of MRAFF process with different nano roughness values are utilized to study its biocompatibility by an in vitro study to examine the cell viability, proliferation of a fibroblast cell line (NIH-3T3) by means of MTT assay. The optical density (OD) values were utilized to determine the amount of viable cells. The cell proliferations studies were conducted and observed for 1, 3 and 7 days of incubation period with respect to the absorbance value of the samples. The protein adsorption studies are also made by using bicinchoninic acid assay (BCA) kit. The characters of biocompatibility are correlated with the nano scale surface roughness parameters of the SS316L samples.
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Godfroy-Cooper, Dr, Francois Denquin, Dr Bachelder, Joel Miller, and Dr Jean. "Influence of Optical and Gravito-Inertial Cues to Height Perception During Supervisory Control." In Vertical Flight Society 76th Annual Forum & Technology Display. The Vertical Flight Society, 2020. http://dx.doi.org/10.4050/f-0076-2020-16417.
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Future vertical lift (FVL) missions will be characterized by increased agility, degraded visual environments (DVE) and optionally piloted vehicles (OPVs). Increased agility will induce more frequent variations of linear and angular accelerations, while DVE will reduce the structure and quality of the out-the-window (OTW) scene (i.e. optical flow). As helicopters become faster and more agile, pilots are expected to navigate at low altitudes while traveling at high speeds. In nap of the earth (NOE) flights, the perception of self-position and orientation provided by visual, vestibular, and proprioceptive cues can vary from moment to moment due to visibility conditions and body alignment as a response to gravitoinertial forces and internally/externally induced perturbations. As a result, erroneous perceptions of the self and the environment can arise, leading ultimately to spatial disorientation (SD). In OPV conditions, the use of different autopilot modes implies a modification of pilot role from active pilot to systems supervisor. This shift in paradigm, where pilotage is not the primary task, and where feedback from the controls is no more available, is not without consequences. Of importance is the evidence that space perception and its geometric properties can be strongly modulated by the active or passive nature of the displacement in space. An experiment was conducted using the vertical motion simulator (VMS) at the NASA Ames Research Center that examined the contributions of gravitoinertial cueing and visual cueing in a task where the pilot was not in control of the aircraft but was asked to perform altitude monitoring in a simulated UH-60 Black Hawk helicopter with a simulated autopilot (AP) mode. Within the altitude monitoring task, the global optical density (OD), flow rate and visual level of detail (LOD) were manipulated by the introduction of an 18ft vertical drift, upward or downward that simulates a vertical wind shift. Seven pilots were tested in two visual meteorological conditions, good visual environment (GVE) and degraded visual environment (DVE) and two gravitoinertial conditions, where platform motion was either ON or OFF. The results showed that both the good quality of the visual environment and the presence of gravitoinertial cues improved altitude awareness and reduced detection/ reaction times. The improvement of the tracking performance in the visuo-vestibular setting as compared to a visual only setting when the visual cues were poor indicated some level of multisensory integration. Task-dependent limitations of a popular aeronautics metric called DIMSS-PM (Dynamic Interface Modeling and Simulation System Product Metric) and its sub-components were shown, and recommendations for OPV operations were formulated.
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Floares, Doris, Diana Obistioiu, Anca Hulea, Ersilia Alexa, and Isidora Radulov. "THUJA OCCIDENTALIS AND PLATYCLADUS ORIENTALIS ANTIMICROBIAL ACTIVITY." In 23rd SGEM International Multidisciplinary Scientific GeoConference 2023. STEF92 Technology, 2023. http://dx.doi.org/10.5593/sgem2023v/6.2/s25.57.
Full textAbstract:
The rise of bacterial resistance to currently employed antibiotics is causing growing concerns for public health. The emergence of highly resistant bacterial strains results in the ineffectiveness of antibiotic treatments against many bacterial infections. As a result, there is an ongoing quest for new antimicrobial agents. This pursuit can take two main directions: one involves the design and synthesis of novel agents, while the other involves exploring natural sources to uncover previously undiscovered antimicrobial compounds. Herbal medications, particularly, have garnered renewed interest due to the perception that they tend to cause fewer adverse reactions when compared to synthetic pharmaceuticals. Moreover, the lower costs of producing plant-based preparations make searching for natural therapeutics appealing. This study aims to assess the antimicrobial properties of Thuja occidentalis (TO) and Platycladus orientalis (PO) against Gram-positive and Gram-negative bacteria using specified reference strains: Streptococcus pyogenes (ATCC 19615), Staphylococcus aureus (ATCC 25923), Listeria monocytogenes (ATCC 19114), Bacillus cereus (ATCC 10876), Clostridium perfringens (ATCC 13124), Shigella flexneri (ATCC 12022), Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 25922), Salmonella typhimurium (ATCC 14028) and Haemophilus influenzae type B (ATCC 10211) Additionally, we determined the minimum inhibitory concentration (MIC). Following ISO 20776-1:2019 guidelines, we assessed the antimicrobial activity by measuring the reduction in microbial mass through spectrophotometry to determine changes in optical density (OD). Our findings indicate that the TO and PO extracts inhibit Gram-positive bacteria, particularly at the initial concentration tested.