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Relevant bibliographies by topics / Optical activity

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Academic literature on the topic 'Optical activity'

Author: Grafiati

Published: 4 June 2021

Last updated: 25 May 2024

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Journal articles on the topic "Optical activity"

1

Blow, Keith. "Optical activity." Nature 359, no. 6394 (October 1992): 454. http://dx.doi.org/10.1038/359454b0.

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Svirko, Yuri, and Nikolay Zheludev. "Reflective optical activity." Faraday Discussions 99 (1994): 359. http://dx.doi.org/10.1039/fd9949900359.

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Nafie, Laurence A. "Vibrational Optical Activity." Applied Spectroscopy 50, no. 5 (May 1996): 14A—26A. http://dx.doi.org/10.1366/0003702963905952.

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Polavarapu, P. L. "Rotational optical activity." Journal of Chemical Physics 86, no. 3 (February 1987): 1136–39. http://dx.doi.org/10.1063/1.452256.

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Blum, K., R. Fandreyer, and D. Thompson. "Electron optical activity." Journal of Physics B: Atomic, Molecular and Optical Physics 23, no. 9 (May 14, 1990): 1519–28. http://dx.doi.org/10.1088/0953-4075/23/9/021.

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Barbieri, A., and E. Guadagnini. "Gravitational optical activity." Nuclear Physics B 703, no. 1-2 (December 2004): 391–99. http://dx.doi.org/10.1016/j.nuclphysb.2004.10.025.

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Barron, Laurence D., and A. David Buckingham. "Vibrational optical activity." Chemical Physics Letters 492, no. 4-6 (June 2010): 199–213. http://dx.doi.org/10.1016/j.cplett.2010.03.090.

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Zuber, Gérard, Peter Wipf, and David N. Beratan. "Exploring the Optical Activity Tensor by Anisotropic Rayleigh Optical Activity Scattering." ChemPhysChem 9, no. 2 (February 1, 2008): 265–71. http://dx.doi.org/10.1002/cphc.200700660.

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Zuber, Gérard, Peter Wipf, and David N. Beratan. "Exploring the Optical Activity Tensor by Anisotropic Rayleigh Optical Activity Scattering." ChemPhysChem 9, no. 4 (March 14, 2008): 504. http://dx.doi.org/10.1002/cphc.200890014.

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Zhang, Shaojun, Zhaobing Tian, Qingpu Wang, Xin Yin, and Shichen Li. "Optimal length of an electro-optical Q-switch with optical activity crystal La3Ga5SiO14." Optics & Laser Technology 39, no. 3 (April 2007): 507–9. http://dx.doi.org/10.1016/j.optlastec.2005.11.003.

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Dissertations / Theses on the topic "Optical activity"

1

Thomas, P. A. "Optical activity in crystals." Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379979.

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Tebbutt, Iain John. "Optical activity and crystal structure." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302911.

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Murphy, Veronica L. "Optical Activity of Achiral Molecules." Thesis, New York University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10192177.

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Optical activity is typically first introduced to a prospective chemist in her sophomore year organic chemistry course. Here, she is taught that optical activity is a consequence of chirality, for example, L-tartaric acid has a specific rotation of +12° at the sodium D-line. However, this leaves said chemist with a wildly skewed and rather vague understanding of the concept of optical activity. There are two major problems with the current understanding of optical activity. The first is that both theory and experiment have shown that optical activity is, in fact, not a consequence of chirality. Molecules belonging to one of four achiral point groups (C_s, C₂_v, S₄, and D₂_d) can display optical activity in particular directions. However, measurement requires an anisotropic medium which presents major challenges. The second problem is that we lack structure-property relationships; specific rotations generally speaking are impossible to connect to molecular structure. Herein, we emphasize optical activity in achiral molecules whose high symmetry and simplified electronic structure are used to establish structure–property relationships. First, achiral optical activity is emphasized by showing that achiral polyaromatic hydrocarbons (PAH) are actually significantly more optically active than their helicene isomers. Next, small, planar, conjugated hydrocarbons are used to interpret optical activity by analysis of their π wave functions that can be intuited from structure. Finally, it is shown that aromaticity is generally deleterious for optical activity. A simple explanation is offered based on Kekule structures.

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Escribano, Rivero Juan Ricardo. "Studies on natural Raman optical activity." Thesis, University of Glasgow, 1985. http://theses.gla.ac.uk/8690/.

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Optical activity associated with vibrations of chiral molecules can provide much stereochemical information. There are two techniques which observe vibrational optical activity (VOA), namely: infrared circular dichroism (IRCD) and vibrational Raman optical activity (VROA). The first, IRCD, is an extension of circular dichroism into the infrared and measures a difference in absorbance of incident left and right circularly polarized infrared radiation. VROA is concerned with a difference in the intensity of Raman scattering when the chiral system is illuminated with left and right circularly polarized radiation. Recent reviews that cover both techniques are in the references of the Summary. This thesis is divided into two main parts. The first (Chapters 1 to 4) is concerned with theoretical studies of ROA. The second (Chapters 5 to 8) with calculations of the observable parameters in VROA and their comparison with experimental results. Chapter 1 comprises a theoretical study in molecular scattering tensors: one significant new result was the discovery of a Stokes-antiStokes asymmetry in the ROA observables. In Chapter 2 is reviewed the experimental conditions in which VROA experiments have been carried out and how the artifacts will affect their spectra. For this, firstly, it has been necessary to provide a general extension of the established equations which give the ROA observables at any point in space. Subsequently a new and more realistic parameter in ROA is defined in terms of power. The difference with the original one is not important in the experimental conditions in which the spectra are recorded, but it is relevant from the scientific aesthetic point of view. Particular cases are derived from these general equations in total agreement with the original and well established ones. In all cases the influence of artifacts coming from imperfectly modulated right and left circularly polarized incident light has been considered. Chapter 3 is a generalization of the "two group model" in VROA using the bond polarizability theory. The model has been extended to include deformations of non-axially symmetric groups. A general critical revision of these formulae is provided. Chapter 4 is a survey of miscellanea in VROA. An interesting prediction is given in the case of Fermi resonance. At the end of this chapter a new selection rule is proposed in VROA which relates polarized and depolarized VROA spectra. This rule is analogous to that which relates polarized and depolarized conventional Raman spectra. The second part of the thesis is devoted to calculations of the observable parameters in VROA and their comparison with the experimental results. The molecule CBrC1FH has not yet been studied experimentally but it is a good (Chapter 5) example for calculations because the results can be compared with those from other theories such as the "atom dipole interaction model". Chapter 6 treats another easy chiral molecule, epoxypropane. The advantage of this molecule is that it can be tested with its experimental spectrum and considering the approximate force field we can say that the comparison is good. Chapters 7 and 8 deal with small chiral molecules derived from cyclohexanone, deuterated and methylated.

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Jonas, Gregory David. "On-line detection of optical activity." Thesis, Birkbeck (University of London), 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286460.

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Zaidi, Syed Anwar Hyder. "Optical Redox Imaging of Metabolic Activity." Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1484672916027993.

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Arzt, Steffi. "Measurements of optical activity and absolute optical chirality in birefringent crystals." Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282424.

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Matos, Gomes E. De. "Relationship between optical activity and crystal structures." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303933.

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Smyth, Edward. "Raman optical activity of proteins and glycoproteins." Thesis, University of Glasgow, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312130.

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Lingard, R. J. "Optical activity in the presence of linear birefringence." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239284.

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Books on the topic "Optical activity"

1

Nafie, Laurence A. Vibrational Optical Activity. Chichester, UK: John Wiley & Sons, Ltd, 2011. http://dx.doi.org/10.1002/9781119976516.

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Molecular light scattering and optical activity. 2nd ed. Cambridge, UK: Cambridge University Press, 2004.

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3

1957-, Lakhtakia A., ed. Selected papers on natural optical activity. Bellingham, Wash., USA: SPIE Optical Engineering Press, 1990.

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4

Vibrational optical activity: Principles and applications. Syracuse, N.Y: Wiley, 2011.

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5

V i atcheslav I. Sokolov. Chirality and optical activity in organometallic compounds. New York: Gordon and Breach Science Publishers, 1990.

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6

Chirality and optical activity in organometallic compounds. New York: Gordon and Breach Science Publishers, 1990.

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7

Charney, Elliot. The molecular basis of optical activity: Optical rotatory dispersion and circular dichroism. Malabar, Fla: R.E. Krieger Pub. Co., 1985.

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8

Polavarapu, Prasad L. Vibrational spectra: Principles and applications with emphasis on optical activity. Amsterdam: Elsevier, 1998.

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George C. Marshall Space Flight Center., ed. System report for the Optical Properties Monitor (OPM) experiment. MSFC, Ala: National Aeronautics and Space Administration, 2001.

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George C. Marshall Space Flight Center., ed. System report for the Optical Properties Monitor (OPM) experiment. MSFC, Ala: National Aeronautics and Space Administration, 2001.

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Book chapters on the topic "Optical activity"

1

Nahler, Gerhard. "optical activity." In Dictionary of Pharmaceutical Medicine, 126. Vienna: Springer Vienna, 2009. http://dx.doi.org/10.1007/978-3-211-89836-9_972.

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Polavarapu, Prasad L. "Vibrational Optical Activity." In Applications of Circularly Polarized Radiation Using Synchrotron and Ordinary Sources, 159–72. Boston, MA: Springer US, 1985. http://dx.doi.org/10.1007/978-1-4757-9229-4_15.

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Gillard, R. D. "Inorganic Optical Activity." In ACS Symposium Series, 286–92. Washington, DC: American Chemical Society, 1994. http://dx.doi.org/10.1021/bk-1994-0565.ch023.

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Vaccaro, Patrick H. "Optical Rotation and Intrinsic Optical Activity." In Comprehensive Chiroptical Spectroscopy, 275–323. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2012. http://dx.doi.org/10.1002/9781118120187.ch11.

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Hansen, Aage E., and Thomas D. Bouman. "Understanding Molecular Optical Activity." In Understanding Molecular Properties, 343–57. Dordrecht: Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-3781-9_22.

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Kuball, H. G., and A. Schönhofer. "Optical Activity of Oriented Molecules." In Polarized Spectroscopy of Ordered Systems, 391–420. Dordrecht: Springer Netherlands, 1988. http://dx.doi.org/10.1007/978-94-009-3039-1_17.

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Grinvald, Amiram, Edmund E. Lieke, Ron D. Frostig, Amos Arieli, Daniel Y. Ts’o, and Rina Hildesheim. "Optical Imaging of Cortical Activity." In Visualization of Brain Functions, 277–88. London: Palgrave Macmillan UK, 1989. http://dx.doi.org/10.1007/978-1-349-10726-1_26.

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Malgrange, Cécile, Christian Ricolleau, and Michel Schlenker. "Rotatory Power and Optical Activity." In Symmetry and Physical Properties of Crystals, 385–406. Dordrecht: Springer Netherlands, 2014. http://dx.doi.org/10.1007/978-94-017-8993-6_18.

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Rogalev, A., J. Goulon, F. Wilhelm, and A. Bosak. "X-Ray Detected Optical Activity." In Springer Proceedings in Physics, 169–90. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-04498-4_6.

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Klebe, Gerhard. "Optical Activity and Biological Effect." In Drug Design, 89–110. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-17907-5_5.

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Conference papers on the topic "Optical activity"

1

Fischer, Peer. "Optical Activity at Interfaces." In Laser Science. Washington, D.C.: OSA, 2009. http://dx.doi.org/10.1364/ls.2009.lsmb2.

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Xu, HongJie, Jun He, BingKun Qin, and Shufen Chen. "Optical activity crystal depolarizer." In Optics and Optoelectronic Inspection and Control: Techniques, Applications, and Instruments, edited by Jinfa Tang, Chao-Nan Xu, and Haizhang Li. SPIE, 2000. http://dx.doi.org/10.1117/12.401672.

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Itoh, N., H. Minemoto, D. Ishiko, and S. Ishizuka. "Commercial Current Sensor Activity in Japan." In Optical Fiber Sensors. Washington, D.C.: OSA, 1997. http://dx.doi.org/10.1364/ofs.1997.owa1.

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Plum, Eric, Xing-Xiang Liu, Vassili A. Fedotov, Yifang Chen, Din P. Tsai, and Nikolay I. Zheludev. "Optical Activity in Achiral Metamaterials." In International Quantum Electronics Conference. Washington, D.C.: OSA, 2009. http://dx.doi.org/10.1364/iqec.2009.itug2.

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Czajkowski, Wojciech, Janusz Parka, Roman S. Dabrowski, and A. Abdulin. "Dichroic dyes with optical activity." In Liquid and Solid State Crystals: Physics, Technology, and Applications, edited by Jozef Zmija. SPIE, 1993. http://dx.doi.org/10.1117/12.156997.

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Fedotov, V. A., E. Plum, A. S. Schwanecke, N. I. Zheludev, and Y. Chen. "Metamaterials with Giant Optical Activity." In 2007 European Conference on Lasers and Electro-Optics and the International Quantum Electronics Conference. IEEE, 2007. http://dx.doi.org/10.1109/cleoe-iqec.2007.4387043.

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Bouakka-Manesse, A., N. Jamin, A. Delannoy, B. Fieque, C. Leroy, P. Pidancier, L. Vial, P. Chorier, and N. Péré-Laperne. "Space activity and programs at SOFRADIR." In SPIE Optical Engineering + Applications, edited by Gary B. Hughes. SPIE, 2016. http://dx.doi.org/10.1117/12.2240657.

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Yi, Sheng, and Hamid Krim. "A curve representation of human activity." In SPIE Optical Engineering + Applications, edited by Vivek K. Goyal, Manos Papadakis, and Dimitri Van De Ville. SPIE, 2009. http://dx.doi.org/10.1117/12.825541.

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Gorti, Viswanath, Ravi Malpani, Emily Blick, Siddharth Khare, Kosar Khaksari, Jules Scholler, Emilie Benoit, Claude Boccara, Dan Sackett, and Amir Gandjbakhche. "DFFOCT As a Tool to Detect Cellular Activity." In Optical Coherence Tomography. Washington, D.C.: OSA, 2020. http://dx.doi.org/10.1364/oct.2020.ow1e.5.

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Shahmirzadi, N. Valizade, A. Fazel Najafabadi, and T. Pakizeh. "Optical activity of heterogeneous plasmonic dimers." In 2017 Iranian Conference on Electrical Engineering (ICEE). IEEE, 2017. http://dx.doi.org/10.1109/iraniancee.2017.7985405.

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Reports on the topic "Optical activity"

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Loew, Leslie M. The Optical Patch Clamp. Stage III. Single Channel Activity by Ultra-Resolution Optics. Fort Belvoir, VA: Defense Technical Information Center, December 2001. http://dx.doi.org/10.21236/ada397457.

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Nessim. L51765 Offshore and Onshore Design Application. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), January 1997. http://dx.doi.org/10.55274/r0010622.

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This report describes the results of a research project on reliability-based optimization of pipeline integrity maintenance activities. The objective was to develop models to quantify the effect of different maintenance activities on the structural reliability of pipelines, and to demonstrate how these models can be used in a relaibility-based framework to develop optimal integrity maintenance plans. The approaches developed can be used to prioritize pipeline segments for maintenance and to select the optimal combination of activites for high priority segments. The maintenance decisions considered include the mainteance method, the time interval between events, and the repair criteria for damage detected by inspection. This report also documents the development of a methodology to quantify the effect of maintenance activities on the structural reliability of pipeline systems.

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Theofanos, Mary Frances. AI Use Taxonomy. Gaithersburg, MD: National Institute of Standards and Technology, 2024. http://dx.doi.org/10.6028/nist.ai.200-1.

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As artificial intelligence (AI) systems continue to be developed, humans will increasingly participate in human-AI interactions. Humans interact with AI systems to achieve particular goals. To ensure that AI systems contribute positively to human-AI interactions, it is important to examine human-AI tasks with an emphasis on human goals and outcomes. The AI Use Taxonomy aims to provide a flexible means of classifying how an AI system contributes to an outcome. The taxonomy sets forward 16 AI use “activities” which are independent of AI techniques and domains. Tasks are combinations of one or more AI use activities. Future research includes applying the taxonomy to better understand measurement challenges for each activity. The taxonomy can contribute to an improved understanding of the architecture of human-AI tasks and help to foster positive, human-centered interactions with AI systems and optimal outcomes.

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Forero-Alvarado, Santiago, Nicolás Moreno-Arias, and Juan J. Ospina-Tejeiro. Humans Against Virus or Humans Against Humans: A Game Theory Approach to the COVID-19 Pandemic. Banco de la República, May 2021. http://dx.doi.org/10.32468/be.1160.

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Externalities and private information are key characteristics of an epidemic like the Covid-19 pandemic. We study the welfare costs stemming from the incomplete information environment that these characteristics foster. We develop a framework that embeds a game theory approach into a macro SIR model to analyze the role of information in determining the extent of the health-economy trade-off of a pandemic. We apply the model to the Covid-19 epidemic in the US and find that the costs of keeping health information private are between USD $5.9$ trillion and USD $6.7$ trillion. We then find an optimal policy of disclosure and divulgation that, combined with testing and containment measures, can improve welfare. Since it is private information about individuals' health what produces the greatest welfare losses, finding ways to make such information known as precisely as possible, would result in significantly fewer deaths and significantly higher economic activity.

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Melnyk, Iurii. RUSSIAN PROPAGANDA ABOUT THE ISRAELI-PALESTINIAN WAR IN 2023: EXAMPLE OF VLADIMIR SOLOVIEV. Ivan Franko National University of Lviv, March 2024. http://dx.doi.org/10.30970/vjo.2024.54-55.12153.

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The purpose of this article is to reconstruct the position of Russian propaganda in the Israeli-Palestinian 2023 war using the example of the media activity of the leading Russian propagandist Vladimir Soloviev. The foreign political circumstances prompted Soloviev to choose a neutral optics of the war. The objects of Soloviev’s accusations turned out to be the Western countries, Ukraine, and Russian political émigrés. Soloviev’s sympathies for Israel came into conflict with the interests of Russian propaganda, for which he works. This contradiction naturally ended with the defeat of his personal sympathies (Israel) before the demands of his employer (Russia). Keywords: Russian propaganda, Vladimir Soloviev, Israel, Palestine, Israeli-Palestinian war, impartiality.

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Taylor. L51724 Fiber Optic Pressure Sensor Development. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), January 1995. http://dx.doi.org/10.55274/r0010368.

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Fiber optic sensors have been under development in industrial and government laboratories around the world for over a decade The commercial market for fiber sensors for measuring parameters such as temperature, displacement, and liquid level is now estimated to exceed $50 M/year Aside from the commercial interest, the U S. Department of Defense has vigorously pursued the development of fiber gyroscopes and hydrophones In spite of the high level of research and devleopment activity, however, fiber sensors were not successfully applied in the relatively harsh environment of engine combustion chambers prior to 1991. The goal of this development is to demonstrate the utilization of a new fiber optic sensor technology in engines used for natural gas transmission. Presently, there is no way to continuously measure pressure in these engines over extended periods of operation. Reliable fiber optic sensor networks supplying data to computerized control systems for on-line engine balancing could lead to major reductions in the emission of NO, and other harmful combustion products. Fuel economies in the millions of dollars per year for companies in the natural gas transmission industry could also be realized.

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Lers, Amnon, and Pamela J. Green. LX Senescence-Induced Ribonuclease in Tomato: Function and Regulation. United States Department of Agriculture, September 2003. http://dx.doi.org/10.32747/2003.7586455.bard.

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Natural leaf senescence, which occurs even when growth conditions are near optimal, has a negative influence on yield. Postharvest induced senescence contributes to the losses of quality in flowers, foliage, and vegetables. Strategies designed to control the senescence process in crop plants could therefore have great applied significance. However, the successful design of such strategies requires a better insight into the senescence machinery and control in higher plants. A main feature of senescence is the hydrolysis of macromolecules by hydrolases of various types such as ribonucleases (RNases) and proteases. Previously we had identified and characterized the tomato LX RNase gene demonstrating its transcript to be highly and specifically induced during senescence. This reported study was focused on LX but also had broadened our research to other senescence-associated nucleic acids degrading enzymes to learn about their function and the regulation of their encoding genes. Beside tomato we used parsley and Arabidopsis for the study of: the bi-functional nuclease which has a role in senescence. The study of different senescence- associated nucleases in few plant systems will allow a more general view on function and regulation of these enzymes in senescence. The specific original proposed objectives included: 1. Study the consequences of alterations in LX RNase level on tomato leaf senescence and general development; 2. Analyze stimuli which may participate in senescence-specific activation of the LX gene; 3. Clone the senescence-associated BFNI nuclease gene homologue from tomato. 4. Further characterize the sequences required for senescence-specific gene expression. Homozygous transgenic plants in which LX gene was either inhibited or over-expressed were generated. In both of these LX mutated plants no major phenotypic consequences were observed, which may suggests that LX is not essential for plant growth under optimal growth conditions. Lack of any abnormalities in the LX over-expressing lines suggests that special system exist to allow function of the RNase only when needed. Detailed analyses of growth under stress and consequences to RNA metabolism are underway. We have analyzed LX expression on the protein level demonstrating that it is involved also in petal senescing. Our results suggest that LX is responding to complex regulation involving developmental, organ dependent factors and responds differently to hormonal or environmental stimuli in the different plant organs. The cloned 1.4 kb promoter was cloned and its analysis revealed that probably not all required elements for senescence induction are included. Biochemical analysis of senescence-associated be-functional nucleases in the different plants, tomato, parsley and Arabidopsis, suggests they belong to a sub-class within the type I plant nucleases. The parsley PcNUC1/2 nuclease protein was purified from senescing leaves its and activity was studied in vitro revealing endo-, double strand, nucleolytic activity and exo-nucleolytic activity. Its encoding gene was cloned and found to be induced on the mRNA level. The promoter of the related Arabidopsis BFNI nuclease was shown in both tomato and Arabidopsis to be able and direct senescence-specific expression suggesting that, at least part, the gene is regulated on the transcriptional level and that the mechanism for this senescence-specific regulation is conserved between different plants. Few plants in which the BFNI gene is mutated were identified which are subjected now to detailed analysis. Our results suggest that the senescence-related nucleic acid degrading enzymes share similarities in both function and regulation between different plants and possibly have important functions in processes un-related to senescence. Still, the function of these enzymes, at least in some cases is not essential to plant development under optimal growth conditions. We are now at the stage which permits in depth investigation of the specific functions and mode of molecular regulation of senescence-associated nucleases with the aid of the research tools developed. The isolated senescence-specific promoter, shown to be active in heterologous plant system, could be utilized in agricultural-related biotechnological applications for retardation of senescence.

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Shomer, Ilan, Louise Wicker, Uzi Merin, and William L. Kerr. Interactions of Cloud Proteins, Pectins and Pectinesterases in Flocculation of Citrus Cloud. United States Department of Agriculture, February 2002. http://dx.doi.org/10.32747/2002.7580669.bard.

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The overall objective was to understand the cloud flocculation of citrus juice by characterization of the interactions between proteins and pectins, and to determine the role of PE isozymes in catalyzing this phenomenon. Specific objectives were to: 1. identify/characterize cloud-proteins in relation to their coagulable properties and affinity to pectins; 2. to determine structural changes of PME and other proteins induced by cation/pectin interactions; 3. localize cloud proteins, PME and bound protein/pectates in unheated and pasteurized juices; 4. to create "sensitized" pectins and determine their effect on clarification. The original objectives were not changed but the methods and approach were modified due to specific research requirements. Two i postulates were: 1. there is a specific interaction of cloud proteins with de-esterified regions of ! pectin and this contributes to cloud loss; 2. isozymes of pectin-methyl-esterase (PME) vary in efficiency to create sensitized pectins. The appearance of citrus fruit juice is an important quality factor and is determined by the color and turbidity that .are conferred by the suspended particles, i.e., by the cloud and its homogeneity. Under some circumstances the cloud tend to flocculate and the juice clarifies. The accepted approach to explain the clarification is based on pectin demethoxylation by PME that promotes formation of Ca-pectate. Therefore, the juice includes immediate heat-inactivation upon ~ squeezing. Protein coagulation also promotes cloud instability of citrus fruit extracts. However, the clarification mechanism is not fully understood. Information accumulated from several laboratories indicates that clarification is a more complex process than can be explained by a single mechanism. The increasing trend to consume natural-fresh juice emphasizing the importance of the knowledge to assure homogeneity of fresh juice. The research included complementary directions: Conditions that induce cloud-instability of natural- juice [IL]. Evaluate purification schemes of protein [USA]. Identifications of proteins, pectin and neutral sugars ([IL]; Structure of the cloud components using light and electron microscopy and immuno-labeling of PME, high-methoxyl-pectin (HMP) and low-methoxyl-pectin (LMP); Molecular weight of calcium sensitized pectins [US]; Evaluation of the products of PME activity [US]. Fractions and size distribution and cloud components [IL-US]. The optimal pH activity of PME is 7 and the flocculation pH of the cloud is 3-4. Thus, the c roles of PME, proteins and pectins in the cloud instability, were studied in pH ranges of 2- 7. The experiments led to establish firstly repeatable simulate conditions for cloud instability [IL]. Thermostable PME (TS-PE) known to induce cloud instability, but also thermolabile forms of PME (TL-PE) caused clarification, most likely due to the formation and dissolution of inactive :. PE-pectin complexes and displacement of a protective colloid from the cloud surface [US]. Furthermore, elimination of non-PME protein increases TS-PE activity, indicating that non-PME proteins moderate PME activity [US]. Other experiments Concomitantly with the study of the PME activity but promotes the association of cloud-proteins to pectin. Adjusting of the juice pH to f 7 retains the cloud stability and re-adjusting of the pH to 40% DE reacts to immuno-labeling in the cloud fragments, whereas

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Sela, Shlomo, and Michael McClelland. Investigation of a new mechanism of desiccation-stress tolerance in Salmonella. United States Department of Agriculture, January 2013. http://dx.doi.org/10.32747/2013.7598155.bard.

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Low-moisture foods (LMF) are increasingly involved in foodborne illness. While bacteria cannot grow in LMF due to the low water content, pathogens such as Salmonella can still survive in dry foods and pose health risks to consumer. We recently found that Salmonella secretes a proteinaceous compound during desiccation, which we identified as OsmY, an osmotic stress response protein of 177 amino acids. To elucidate the role of OsmY in conferring tolerance against desiccation and other stresses in Salmonella entericaserovarTyphimurium (STm), our specific objectives were: (1) Characterize the involvement of OsmY in desiccation tolerance; (2) Perform structure-function analysis of OsmY; (3) Study OsmY expression under various growth- and environmental conditions of relevance to agriculture; (4) Examine the involvement of OsmY in response to other stresses of relevance to agriculture; and (5) Elucidate regulatory pathways involved in controlling osmY expression. We demonstrated that an osmY-mutant strain is impaired in both desiccation tolerance (DT) and in long-term persistence during cold storage (LTP). Genetic complementation and addition of a recombinantOsmY (rOsmY) restored the mutant survival back to that of the wild type (wt). To analyze the function of specific domains we have generated a recombinantOsmY (rOsmY) protein. A dose-response DT study showed that rOsmY has the highest protection at a concentration of 0.5 nM. This effect was protein- specific as a comparable amount of bovine serum albumin, an unrelated protein, had a three-time lower protection level. Further characterization of OsmY revealed that the protein has a surfactant activity and is involved in swarming motility. OsmY was shown to facilitate biofilm formation during dehydration but not during bacterial growth under optimal growth conditions. This finding suggests that expression and secretion of OsmY under stress conditions was potentially associated with facilitating biofilm production. OsmY contains two conserved BON domains. To better understand the role of the BON sites in OsmY-mediated dehydration tolerance, we have generated two additional rOsmY constructs, lacking either BON1 or BON2 sites. BON1-minus (but not BON2) protein has decreased dehydration tolerance compared to intact rOsmY, suggesting that BON1 is required for maximal OsmY-mediated activity. Addition of BON1-peptide at concentration below 0.4 µM did not affect STm survival. Interestingly, a toxic effect of BON1 peptide was observed in concentration as low as 0.4 µM. Higher concentrations resulted in complete abrogation of the rOsmY effect, supporting the notion that BON-mediated interaction is essential for rOsmY activity. We performed extensive analysis of RNA expression of STm undergoing desiccation after exponential and stationary growth, identifying all categories of genes that are differentially expressed during this process. We also performed massively in-parallel screening of all genes in which mutation caused changes in fitness during drying, identifying over 400 such genes, which are now undergoing confirmation. As expected OsmY is one of these genes. In conclusion, this is the first study to identify that OsmY protein secreted during dehydration contributes to desiccation tolerance in Salmonella by facilitating dehydration- mediated biofilm formation. Expression of OsmY also enhances swarming motility, apparently through its surfactant activity. The BON1 domain is required for full OsmY activity, demonstrating a potential intervention to reduce pathogen survival in food processing. Expression and fitness screens have begun to elucidate the processes of desiccation, with the potential to uncover additional specific targets for efforts to mitigate pathogen survival in desiccation.

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Liang, Jinghong, Yu Zhao, Yican Chen, Shuxin Zhang, Kaiyun Tan, Jingshu Zhang, Aerziguli Kakaer, and Yajun Chen. Face-to-face Physical activity incorporated with Dietary intervention may be the optimal intervention strategy for preventing obesity among children and adolescents ― Evidence from Bayesian Network Meta-analysis of 118 randomized controlled trials with 71,064 individuals. INPLASY - International Platform of Registered Systematic Review and Meta-analysis Protocols, February 2021. http://dx.doi.org/10.37766/inplasy2021.2.0072.

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