Articles de revues : « Nucleus ruber »

1

Nakayama, Tomoya, Satoshi Miyajima, Hirotaka Nishino, Junya Narita, Hideki Abe et Naoyuki Yamamoto. « Nucleus Ruber of Actinopterygians ». Brain, Behavior and Evolution 88, n^o 1 (2016) : 25–42. http://dx.doi.org/10.1159/000447442.

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Nucleus ruber is known as an important supraspinal center that controls forelimb movements in tetrapods, and the rubral homologue may serve similar functions in fishes (motor control of pectoral fin). However, two apparently different structures have been identified as ‘nucleus ruber' in actinopterygians. One is nucleus ruber of Goldstein (1905) (NRg), and the other nucleus ruber of Nieuwenhuys and Pouwels (1983) (NRnp). It remains unclear whether one of these nuclei (or perhaps both) is homologous to tetrapod nucleus ruber. To resolve this issue from a phylogenetic point of view, we have investigated the distribution of tegmental neurons retrogradely labeled from the spinal cord in eight actinopterygian species. We also investigated the presence/absence of the two nuclei with Nissl- or Bodian-stained brain section series of an additional 28 actinopterygian species by comparing the morphological features of candidate rubral neurons with those of neurons revealed by the tracer studies. Based on these analyses, the NRg was identified in all actinopterygians investigated in the present study, while the NRnp appears to be absent in basal actinopterygians. The phylogenetic distribution pattern indicates that the NRg is the more likely homologue of nucleus ruber, and the NRnp may be a derived nucleus that emerged during the course of actinopterygian evolution.

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Gorges, M., J. Kassubek et H. Graf. « Hypertrophe Degeneration des Nucleus olivaris ». Nervenheilkunde 32, n^o 08 (août 2013) : 532–37. http://dx.doi.org/10.1055/s-0038-1628538.

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ZusammenfassungDie hypertrophe Degeneration der Oliven (HOD) ist eine seltene Form der Neuroplastizität, die als Folge von Läsionen des anatomisch-funktionellen Regelkreises des Guillan-Mollaret-Dreiecks, bestehend aus dem Nucleus ruber, dem ipsilateralen Nucleus olivaris inferior (ION) und dem kontralateralen Nucleus dentatus, auftritt. Dieser Artikel zeigt eine Übersicht der Literatur der HOD unter Berücksichtigung ätiologischer, pathophysiologischer und klinischer Aspekte. Darüber hinaus berichten wir von einem Patienten mit HOD, der mittels Videookulografie untersucht wurde.

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Matsui, Hideaki. « Dopamine system, cerebellum, and nucleus ruber in fish and mammals ». Development, Growth & ; Differentiation 59, n^o 4 (mai 2017) : 219–27. http://dx.doi.org/10.1111/dgd.12357.

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Baldanta, Sara, Juana María Navarro Llorens et Govinda Guevara. « Further Studies on the 3-Ketosteroid 9α-Hydroxylase of Rhodococcus ruber Chol-4, a Rieske Oxygenase of the Steroid Degradation Pathway ». Microorganisms 9, n^o 6 (29 mai 2021) : 1171. http://dx.doi.org/10.3390/microorganisms9061171.

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The biochemistry and genetics of the bacterial steroid catabolism have been extensively studied during the last years and their findings have been essential to the development of biotechnological applications. For instance, metabolic engineering of the steroid-eater strains has allowed to obtain intermediaries of industrial value. However, there are still some drawbacks that must be overcome, such as the redundancy of the steroid catabolism genes in the genome and a better knowledge of its genetic regulation. KshABs and KstDs are key enzymes involved in the aerobic breakage of the steroid nucleus. Rhodococcus ruber Chol-4 contains three kshAs genes, a single kshB gene and three kstDs genes within its genome. In the present work, the growth of R. ruber ΔkshA strains was evaluated on different steroids substrates; the promoter regions of these genes were analyzed; and their expression was followed by qRT-PCR in both wild type and ksh mutants. Additionally, the transcription level of the kstDs genes was studied in the ksh mutants. The results show that KshA2B and KshA1B are involved in AD metabolism, while KshA3B and KshA1B contribute to the cholesterol metabolism in R. ruber. In the kshA single mutants, expression of the remaining kshA and kstD genes is re-organized to survive on the steroid substrate. These data give insight into the fine regulation of steroid genes when several isoforms are present.

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Nakayama, Tomoya, Hirotaka Nishino, Junya Narita, Hideki Abe et Naoyuki Yamamoto. « Indirect pathway to pectoral fin motor neurons from nucleus ruber in the Nile tilapia Oreochromis niloticus ». Journal of Comparative Neurology 527, n^o 5 (13 décembre 2018) : 957–71. http://dx.doi.org/10.1002/cne.24578.

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Naujoks-Manteuffel, Christiane, Gerhard Manteuffel et Werner Himstedt. « On the presence of nucleus ruber in the urodele Salamandra salamandra and the caecilian Ichthyophis kohtaoensis ». Behavioural Brain Research 28, n^o 1-2 (avril 1988) : 29–32. http://dx.doi.org/10.1016/0166-4328(88)90074-5.

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Skofitseh, Gerhard, Wolfgang Gubisch, Sunil J. Wimalawansa et David M. Jacobowitz. « Comparative immunohistochemical distribution of amylin-like and calcitonin gene related peptide like immunoreactivity in the rat central nervous system ». Canadian Journal of Physiology and Pharmacology 73, n^o 7 (1 juillet 1995) : 945–56. http://dx.doi.org/10.1139/y95-131.

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Using the indirect immunofluorescence method with a polyclonal antiserum raised in rabbits and directed against amylin (AMY), we have investigated the distribution of AMY-like immunoreactivity (-ir) throughout the central nervous system of the rat. The widespread distribution of AMY-ir was much more abundant than that previously reported for calcitonin gene related peptide (CGRP) immunoreactivity. In most brain areas there was no overlap between AMY- and CGRP-ir cell body groupings, with the exception of the motor nuclei of the hindbrain and spinal cord, which were found to contain large numbers of AMY- and CGRP-immunoreactive cell bodies. Areas with a moderate to dense appearance of AMY-ir were the rhinencephalon, the nucleus of the diagonal band, the magnocellular, dorso- and ventro-medial and mammillary nuclei of the hypothalamus, the habenula, the compact part of the substantia nigra, the ruber and pontine nuclei, and the inferior olive and the cerebellar nuclei. The widespread immunohistochemical distribution of AMY-ir in the rat brain is in partial agreement with the distribution of AMY-binding sites.Key words: calcitonin gene related peptide, amylin, central nervous system, immunohistochemistry, rat.

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Costa, Stefania, Federico Zappaterra, Daniela Summa, Bruno Semeraro et Giancarlo Fantin. « Δ1-Dehydrogenation and C20 Reduction of Cortisone and Hydrocortisone Catalyzed by Rhodococcus Strains ». Molecules 25, n^o 9 (7 mai 2020) : 2192. http://dx.doi.org/10.3390/molecules25092192.

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Prednisone and prednisolone are steroids widely used as anti-inflammatory drugs. Development of the pharmaceutical industry is currently aimed at introducing biotechnological processes and replacing multiple-stage chemical syntheses. In this work we evaluated the ability of bacteria belonging to the Rhodococcus genus to biotransform substrates, such as cortisone and hydrocortisone, to obtain prednisone and prednisolone, respectively. These products are of great interest from a pharmaceutical point of view as they have higher anti-inflammatory activity than the starting substrates. After an initial lab-scale screening of 13 Rhodococcus strains, to select the highest producers of prednisone and prednisolone, we reported the 200 ml-batch scale-up to test the process efficiency and productivity of the most promising Rhodococcus strains. R. ruber, R. globerulus and R. coprophilus gave the Δ1-dehydrogenation products of cortisone and hydrocortisone (prednisone and prednisolone) in variable amounts. In these biotransformations, the formation of products with the reduced carbonyl group in position C20 of the lateral chain of the steroid nucleus was also observed (i.e., 20β-hydroxy-prednisone and 20β-hydroxy-prednisolone). The yields, the absence of collateral products, and in some cases the absence of starting products allow us to say that cortisone and hydrocortisone are partly degraded.

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Stephenson, R., D. R. Jones et R. M. Bryan. « Regional cerebral blood flow during submergence asphyxia in Pekin duck ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 266, n^o 4 (1 avril 1994) : R1162—R1168. http://dx.doi.org/10.1152/ajpregu.1994.266.4.r1162.

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The cerebrovascular response to submergence asphyxia was studied in the Pekin duck (Anas platyrhynchos var.) by use of the cerebral blood flow (CBF) tracer [14C]isopropyliodoamphetamine and quantitative autoradiography. Blood flow of the whole brain was 158 +/- 14 (SE) ml.min-1 x 100 g-1 (n = 7) in control animals. There was a doubling of flow to 320 +/- 61 ml.min-1 x 100 g-1 (n = 6) during submergence asphyxia. The hypothesis that CBF is redistributed within the brain during asphyxia was not supported. There were no regional reductions in CBF during submergence asphyxia. Mean arterial blood pressure was similar (approximately 140 mmHg), but heart rate, arterial blood gas tensions, and arterial pH were significantly different in control and submerged ducks at the time CBF was measured. The differences in CBF among submerged animals correlated strongly with arterial PCO2 and mean arterial blood pressure. The smallest proportional difference in regional CBF between control and submerged ducks occurred in the ectostriatum (+141%) and the largest in the locus ceruleus (+241%). The largest absolute difference in regional CBF was in the nucleus ruber (+322 ml.min-1 x 100 g-1). These are the first measurements of blood flow in discrete nuclei and regions of the avian brain.

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Lomakin, A. J., C. J. Cattin, D. Cuvelier, Z. Alraies, M. Molina, G. P. F. Nader, N. Srivastava et al. « The nucleus acts as a ruler tailoring cell responses to spatial constraints ». Science 370, n^o 6514 (15 octobre 2020) : eaba2894. http://dx.doi.org/10.1126/science.aba2894.

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The microscopic environment inside a metazoan organism is highly crowded. Whether individual cells can tailor their behavior to the limited space remains unclear. In this study, we found that cells measure the degree of spatial confinement by using their largest and stiffest organelle, the nucleus. Cell confinement below a resting nucleus size deforms the nucleus, which expands and stretches its envelope. This activates signaling to the actomyosin cortex via nuclear envelope stretch-sensitive proteins, up-regulating cell contractility. We established that the tailored contractile response constitutes a nuclear ruler–based signaling pathway involved in migratory cell behaviors. Cells rely on the nuclear ruler to modulate the motive force that enables their passage through restrictive pores in complex three-dimensional environments, a process relevant to cancer cell invasion, immune responses, and embryonic development.

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Hajjaj, Hassan, Alain Klaébé, Marie O. Loret, Gérard Goma, Philippe J. Blanc et Jean François. « Biosynthetic Pathway of Citrinin in the Filamentous Fungus Monascus ruber as Revealed by 13C Nuclear Magnetic Resonance ». Applied and Environmental Microbiology 65, n^o 1 (1 janvier 1999) : 311–14. http://dx.doi.org/10.1128/aem.65.1.311-314.1999.

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ABSTRACT Carbon isotope distribution of [13C]citrinin fromMonascus ruber incubated with [13C]acetate revealed that the biosynthesis of the toxin originated from a tetraketide, instead of a pentaketide as has been shown forPenicillium and Aspergillus species. The production of polyketide red pigments and citrinin by M. ruber may therefore be regulated at the level of the tetraketide branch point.

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Hanthanon, Pran, Thiti Kaisone, Chanon Wiphanurat et Tarinee Nampitch. « Knowledge Management of Net Requirements in Using Natural Rubber in Thai Rubber Industry to Support the Increase in Using Natural Rubber within Thailand ». Applied Mechanics and Materials 851 (août 2016) : 117–21. http://dx.doi.org/10.4028/www.scientific.net/amm.851.117.

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A blend of natural rubber (NR) and styrene butadiene rubber (SBR) was tested against conventional rubber products sold in department stores and markets, using nuclear magnetic resonance (NMR) spectroscopy to measure the amount of natural or synthetic rubber in the product. 1H-NMR spectroscopy was employed for the rubber blend and 13C-NMR spectroscopy for conventional products. The chemical shift of all the samples from the structure of natural rubber (cis-1,4 polyisoprene) was observed.

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Kantee, Jutamas, et Somjai Kajorncheappunngam. « Characterization of Epoxidized Rubber Seed Oil ». Key Engineering Materials 728 (janvier 2017) : 295–300. http://dx.doi.org/10.4028/www.scientific.net/kem.728.295.

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Epoxidation of rubber seed oil was carried out using a peroxyacid generated in situ from glacial acetic acid and hydrogen peroxide to produce epoxidized rubber seed oil. The maximum relative conversion to oxirane of 88 % could be obtained at 60 °C after a reaction time of 7 hours. The presence of oxirane ring of epoxidized rubber seed oil was confirmed by fourier transform infrared spectrometer (FT-IR) and proton nuclear magnetic resonance (1H NMR) spectra analysis which displayed a disappearance of double bonds peak in rubber seed oil and an existing of epoxide ring peak in epoxidized rubber seed oil.

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Mohamad Aini, Nor, Nadras Othman, M. Hussin, Kannika Sahakaro et Nabil Hayeemasae. « Hydroxymethylation-Modified Lignin and Its Effectiveness as a Filler in Rubber Composites ». Processes 7, n^o 5 (25 mai 2019) : 315. http://dx.doi.org/10.3390/pr7050315.

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Kraft lignin was modified by using hydroxymethylation to enhance the compatibility between rubber based on a blend of natural rubber/polybutadiene rubber (NR/BR) and lignin. To confirm this modification, the resultant hydroxymethylated kraft lignin (HMKL) was characterized using Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy. It was then incorporated into rubber composites and compared with unmodified rubber. All rubber composites were investigated in terms of rheology, mechanical properties, aging, thermal properties, and morphology. The results show that the HMKL influenced the mechanical properties (tensile properties, hardness, and compression set) of NR/BR composites compared to unmodified lignin. Further evidence also revealed better dispersion and good interaction between the HMKL and the rubber matrix. Based on its performance in NR/BR composites, hydroxymethylated lignin can be used as a filler in the rubber industry.

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DeGaspari, John. « Nukes and Rubber ». Mechanical Engineering 124, n^o 11 (1 novembre 2002) : 54–56. http://dx.doi.org/10.1115/1.2002-nov-4.

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This article focuses on the behavior of tires that appears to have little in common with expectations for nuclear weapons. However, they are similar enough that Sandia National Laboratories and Goodyear Tire and Rubber Co. are working together and sharing the same tools to understand their different products. Sandia uses computational mechanics to simulate phenomena such as non-linear mechanics, to predict how a component will perform when it is slammed into the ground. The biggest challenge in computational mechanics is to convince the engineer that we have captured all of the relevant physics that computational simulation is every bit as good as or better than the same experiment being performed.

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Zhang, Fu Quan, Yong Zhou Wang, Mei Chen, Mao Fang Huang et Ri Zhong Zeng. « Study on Crosslink Density of Natural Rubber with Different Initial Moisture Contents Dried by Microwave ». Applied Mechanics and Materials 556-562 (mai 2014) : 173–76. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.173.

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In this work, the crosslink density of uncured natural rubber with different initial moisture contents, 3.80%, 10.05%, 19.76%, 23.68%, respectively, dried by microwave at frequency of 2450MHz was studied using nuclear magnetic resonance spectrometer. Seen from the results, the effect of initial moisture content of wet natural rubber on crosslink density and processability were obvious. With the increment of initial moisture content of wet natural rubber, the crosslink density of natural rubber after microwave dried with the frequency of 2450MHz decreased gradually. The crosslink density and A(Mc) of natural with the lower initial moisture content was bigger compared with natural rubber with the higher initial moisture content.

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Fujita, Takafumi. « Seismic isolation rubber bearings for nuclear facilities ». Nuclear Engineering and Design 127, n^o 3 (juin 1991) : 379–91. http://dx.doi.org/10.1016/0029-5493(91)90062-m.

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Li, Yuanyuan, Shuzhi Sam Ge, Kun Mo et Biao Liu. « Effect of radiation on mechanical properties and molecular structure of rubbers for nuclear robots ». Materials Express 11, n^o 9 (1 septembre 2021) : 1561–70. http://dx.doi.org/10.1166/mex.2021.1897.

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As polymers, rubber materials are easily affected by radiation; therefore, their radiation resistance must be considered for their use in robots and automation equipment in high-radiation environments. In this study, the properties of several common rubber materials, ethylene propylene diene monomer (EPDM), nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), fluororubber (FKM), and acrylate rubber (ACM), were investigated under high-dose gamma-ray irradiation. The dose rate of gamma rays was 66.76 Gy/min, and the cumulative dose was 1214965.24 Gy. Oxidative decomposition of the double bond of EPDM occurred, leading to slight decreases in the strength and elongation. NBR and HNBR were mainly subjected to crosslinking of the molecular structure, resulting in small increases in strength and significant decreases in elongation. The cyano decomposition reaction occurred in ACM, and its crystallinity increased, leading to embrittlement and decreases in the strength and elongation. Oxidative decomposition and cross-linking simultaneously occurred in FKM, resulting in an increase in strength and decreases in elongation and the elastic modulus.

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Riyajan, Sa-ad, Yasuyuki Tanaka et Jitladda T. Sakdapipanich. « Preparation of Cyclized Deproteinized Natural Rubber in Latex State via a Combination of Benzotrichloride and Sulfuric Acid System, and Its Properties ». Rubber Chemistry and Technology 80, n^o 2 (1 mai 2007) : 365–77. http://dx.doi.org/10.5254/1.3539412.

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Abstract Partially cyclized deproteinized natural rubber (DPNR) in latex form was successfully prepared by using a combination of sulfuric acid (H2SO4) and benzotrichloride (PhCCl3) in the presence of Terric 320 as a non-ionic surfactant. The main parameters of the cyclization process such as various reaction times, dry rubber contents, concentrations of catalyst and temperatures were investigated. The resulting rubber was subjected to characterization by proton Nuclear Magnetic Resonance (1H-NMR), Fourier-Transform Infrared spectrometer (FTIR), Thermal Gravimetric Analysis (TGA), and Differential Scan Calorimeter (DSC). In addition, the topology of partially cyclized rubber was also analyzed by Transmittance Electron Microscopy (TEM). The mechanism will be also discussed. It was interesting to note that the obtained partially cyclized rubber using this catalyst system contained no gel, which was easily soluble in rubber solvents. This is different from the partially cyclized rubber obtained from the other methods. Through, using structural characterization, it was found that the PhCCl3 linked onto the rubber chain. It was also found that the thermal stability of this cyclized rubber was better than that of normal rubber. The efficiency of cyclization in this system could be increased by an increase of PhCCl3 concentration.

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Song, Shouxu, Hui Zha et Haihong Huang. « Cavitation desulfurization in vulcanized rubber recycling under ultra-high pressure water jet ». Journal of Polymer Engineering 37, n^o 5 (24 mai 2017) : 529–36. http://dx.doi.org/10.1515/polyeng-2016-0103.

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Abstract Ultra-high pressure water jet is proposed for recycling of vulcanized waste rubber, and cavitation desulfurization in the recycling process is analyzed. The chemical effects of mechanical shearing, pyrolysis, free radical oxidation, and supercritical oxidation produced by bubble collapse are considered the main causes of desulfurization. Scanning electron microscopy, Fourier transform infrared spectrometry, differential scanning calorimetry, nuclear magnetic resonance test, and X-ray photoelectron spectroscopy are used to determine the performance of rubber powder. Gel fraction of rubber powder is measured to analyze the effect of jet pressure on desulfurization. Results indicate that the vulcanized rubber could achieve partial desulfurization. The glass transition temperature of the rubber powder slightly increases after crushing. With the increase of jet pressure, the gel fraction of rubber powder initially decreases and then increases, as well as achieves a minimum value at the jet pressure of nearly 220 MPa, which is ideal for desulfurization.

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Uhlig, K., et W. Hehn. « Rubber band suspension for a nuclear demagnetization cryostat ». Cryogenics 28, n^o 9 (septembre 1988) : 612–14. http://dx.doi.org/10.1016/0011-2275(88)90215-9.

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Borsacchi, Silvia, Umayal Sudhakaran, Lucia Calucci, Francesca Martini, Elisa Carignani, Massimo Messori et Marco Geppi. « Rubber-Filler Interactions in Polyisoprene Filled with In Situ Generated Silica : A Solid State NMR Study ». Polymers 10, n^o 8 (25 juillet 2018) : 822. http://dx.doi.org/10.3390/polym10080822.

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In this paper we used high- and low-resolution solid state Nuclear Magnetic Resonance (NMR) techniques to investigate a series of polyisoprene samples filled with silica generated in situ from tetraethoxysilane by sol-gel process. In particular, 1H spin-lattice and spin-spin relaxation times allowed us to get insights into the dynamic properties of both the polymer bulk and the bound rubber, and to obtain a comparative estimate of the amount of bound rubber in samples prepared with different compositions and sol-gel reaction times. In all samples, three fractions with different mobility could be distinguished by 1H T2 and ascribed to loosely bound rubber, polymer bulk, and free chain ends. The amount of bound rubber was found to be dependent on sample preparation, and it resulted maximum in the sample showing the best dispersion of silica domains in the rubber matrix. The interpretation of the loosely bound rubber in terms of “glassy” behaviour was discussed, also on the basis of 1H T1 and T1ρ data.

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Ren, Hong-Yuan, Zheng Sun, Li-Qun Zhang, You-Ping Wu, Qiang Huang et You-Zhi Wang. « EFFECTS OF SILANE COUPLING AGENTS ON STRUCTURE AND PROPERTIES OF SILICA-FILLED SILICONE RUBBER/STYRENE BUTADIENE RUBBER COMPOSITES ». Rubber Chemistry and Technology 91, n^o 2 (1 avril 2018) : 453–68. http://dx.doi.org/10.5254/rct.18.81657.

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ABSTRACT Two silane coupling agents, bis-(γ-triethoxysilylpropyl)-tetrasulfide (Si69) and vinyltriethoxysilane (A151), were selected to investigate their effects on structure and properties of silica-filled methyl vinyl silicone rubber (VMQ)/emulsion styrene butadiene rubber (ESBR) composites. The filler–rubber interactions were investigated via bound rubber content and solid-state 1H low-field nuclear magnetic resonance (NMR) spectroscopy, and the mass ratio of VMQ and ESBR in the rubber–filler gel was investigated by thermogravimetric analysis (TGA). The results revealed that VMQ showed a better compatibility with silica than ESBR. Compared with the A151 composite, the composite with Si69 showed the higher content of ESBR in rubber–filler gel, which resulted in the higher bound rubber content and the weaker Payne effect, and it also exhibited higher tensile strength, higher tear strength, better wear resistance, and lower hardness. However, the presence of Si69 reduced the crosslink efficiency of ESBR and completely inhibited the crosslinking of VMQ, which caused the composite to show higher tan δ value at 60 °C than the A151 composite.

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De Sarkar, Mousumi, Wataru Nishino, Yuhei Ishigaki et Takashi Sunada. « Introduction to the New Copolymer of Chloroprene and Acrylonitrile with Differentiated Properties ». Advances in Polymer Technology 2021 (21 juillet 2021) : 1–17. http://dx.doi.org/10.1155/2021/9955850.

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The random copolymer of chloroprene and acrylonitrile is a newly developed rubber whose features and value propositions are not scientifically explored yet. This article focuses on the basic characterizations and properties of acrylonitrile-chloroprene rubber. Qualitative analyses through infrared (FTIR) and nuclear magnetic resonance (1H-NMR) spectra confirm the presence of both the -Cl and -CN groups in the new rubber. As evidenced through differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA), the single glass transition temperature of acrylonitrile-chloroprene rubber reflects its monophasic random microstructure. While compared against commercial grades of chloroprene rubber (CR) and nitrile rubber (NBR), the new rubber provides a distinctive combination of properties that are not available with either of the elastomer alone. Acrylonitrile-chloroprene rubber demonstrates slightly lower specific gravity, an improved low-temperature compression set, higher flex-fatigue resistance, and lower volume swelling in IRM 903 and Fuel C to chloroprene rubber. As compared to nitrile rubber, the new copolymer shows appreciably better heat aging and ozone resistance. Good abrasion resistance, low heat buildup, and remarkably high flex-fatigue resistance indicate excellent durability of the acrylonitrile-chloroprene rubber under dynamic loading. Based on the preliminary results, it is apparent that the new copolymer can be a candidate elastomer for various industrial applications which demand good fluid resistance, high heat and low-temperature tolerances, good weatherability, and durability under static and dynamic conditions.

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Anderson, Alistair J., D. Roger Williams, Edwin A. Dawes et David F. Ewing. « Biosynthesis of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) in Rhodococcus ruber ». Canadian Journal of Microbiology 41, n^o 13 (15 décembre 1995) : 4–13. http://dx.doi.org/10.1139/m95-162.

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The biosynthesis of the 3-hydroxyvalerate (3HV) monomer of the polyhydroxyalkanoate produced from glucose by Rhodococcus ruber was investigated using nuclear magnetic resonance analysis. Spectra obtained for polymer produced from [6-13C]-, [2-13C]-, and [1-13C]glucose were compatible with carboxylation of pyruvate followed by TCA cycle reactions to yield succinate, which is a precursor of propionyl-CoA in the biosynthesis of 3HV in this organism. Carboxylation of pyruvate may occur directly or involve methylmalonyl-CoA transcarboxylase but the latter process is more probable as it provides a route for recycling oxaloacetate, which is essential for the pathway to operate. The observed incorporation of label from NaH13CO3 into C-3 of 3HV monomers cannot occur via forward reactions of the TCA cycle but may be explained by direct carboxylation of pyruvate, followed by reverse reactions of the TCA cycle to yield succinyl-CoA. This minor route accounts for at least 12% of the carbon flux in the synthesis of 3HV monomer units. Inhibitors of key enzymes of possible pathways for polyhydroxyalkanoate biosynthesis in R. ruber were tested. Addition of monofluoroacetate, an inhibitor of aconitase, to cultures decreased production of 3HV, supporting the proposed major route for 3HV synthesis.Key words: Rhodococcus ruber, polyhydroxyalkanoate, PHA, biosynthesis.

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Wu, Xiaofei, Ping Liu et Zhigang Ge. « Implementation of Probability Table Generation Using Ladder Method in Ruler ». EPJ Web of Conferences 239 (2020) : 10005. http://dx.doi.org/10.1051/epjconf/202023910005.

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Probability table is one of the most important and natural methods used to simulate the neutron transport in unresolved resonance range in reactor physics. A new module for generating probability tables in the unresolved-resonance region has been developed for the nuclear data processing code Ruler, using ladder method. In order to validate and verify the accuracy of this module, Probability tables have been calculated and compared with NJOY2016. Agreement is observed in the comparisons of the probability tables and corresponding cross-section values that are calculated by Ruler and NJOY2016. Ruler has improved computational efficiency greatly comparing with NJOY2016 as multi-thread parallel algorithm is applied.

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Thi Thuong, Nghiem, Phan Trung Nghia et Seiichi Kawahara. « Factors influencing green strength of commercial natural rubber ». Green Processing and Synthesis 7, n^o 5 (25 octobre 2018) : 399–403. http://dx.doi.org/10.1515/gps-2018-0019.

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Abstract The factors influencing the green strength of commercial solid rubbers were investigated in the present study through characterization of commercial natural rubber (NR). Various solid commercial rubbers such as standard Vietnam rubber (SVR10), standard Indonesia rubber (SIR10), India standard natural rubber (ISNR10), ribbed smoked sheets (RSS3), and FNR (commercial Sumitomo Rubber) were used as a source. Purification of the samples was carried out through acetone extraction and purified samples were characterized by nuclear magnetic resonance (NMR) and Fourier-Transform infrared spectroscopy. Degradation was found for SVR10, ISNR10, and SIR10 but not for RSS3 and FNR through the assignment of 13C-NMR signals. Acetone extraction was found to improve the green strength of commercial NR due to the removal of impurities. Linked fatty acids and proteins contributed to the upturn of stress at small strain. However, the network structure of degraded rubbers had an insignificant role in enhancing the green strength of commercial NR.

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Rohani, Abu Bakar, Mustafa Kamal Mazlina et Fauzi Mohd Som. « Effect of Methyl Methacrylate Content in Carbon Black Filled Natural Rubber Compounds ». Advanced Materials Research 501 (avril 2012) : 3–7. http://dx.doi.org/10.4028/www.scientific.net/amr.501.3.

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Natural rubber-grafted-poly(methyl methacrylate) containing 30 and 50 percent of methyl methacrylate (MMA) monomer per 100 parts by weight of the dry rubber content denoted as NR-g-PMMA 30 and NR-g-PMMA 50, respectively were prepared via emulsion polymerisation technique. The occurrences of graft copolymerisation of PMMA onto NR were confirmed by proton Nuclear Magnetic Resonance (1H NMR) and Fourier Transform Infrared (FTIR) following purifications. The reinforcement of rubber by fillers is of great practical and technical importance. Thus, these fillers are added to rubber formulations to optimize the properties to meet a given application or set of performance parameters. In this study, the effect of carbon black in NR-g-PMMA 30 and NR-g-PMMA 50 rubber compounds were evaluated. Our results demonstrated that tensile strength, elongation at break and compression set reduced, while the hardness and solvent resistance increased in the presence of carbon black filler in comparison to the unfilled compound.

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Silva, Leonardo A. da, Daniel M. P. Ardisson-Araújo, Brenda R. de Camargo, Marlinda Lobo de Souza et Bergmann M. Ribeiro. « A novel cypovirus found in a betabaculovirus co-infection context contains a poxvirus immune nuclease (poxin)-related gene ». Journal of General Virology 101, n^o 6 (1 juin 2020) : 667–75. http://dx.doi.org/10.1099/jgv.0.001413.

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The cassava hornworm Erinnyis ello ello (Lepidoptera: Sphingidae) is an important pest in Brazil. This insect feeds on host plants of several species, especially Manihot esculenta (cassava) and Hevia brasiliensis (rubber tree). Cassava hornworm outbreaks are quite common in Brazil and can cause great impact over crop production. Granulare and polyhedral-shaped occlusion bodies (OBs) were observed in extracts of dead E. ello larvae from rubber-tree plantations by light and scanning electron microscopy (SEM), suggesting a mixed infection. The polyhedral-shaped OB surface revealed indentations that resemble those found in cypovirus polyhedra. After OB nucleic acid extraction followed by cDNA production and Illumina deep-sequencing analysis, the results confirmed for the presence of a putative novel cypovirus that carries ten segments and also a betabaculovirus (Erinnyis ello granulovirus, ErelGV). Phylogenetic analysis of the predicted segment 1-enconded RdRP showed that the new cypovirus isolate is closely related to a member of species Cypovirus 2, which was isolated from Inachis io (Lepidoptera: Nymphalidae). Therefore, we named this new isolate Erinnyis ello cypovirus 2 (ErelCPV-2). Genome in silico analyses showed that ErelCPV-2 segment 8 (S8) has a predicted amino acid identity of 35.82 % to a hypothetical protein of betabaculoviruses. This putative protein has a cGAMP-specific nuclease domain related to the poxvirus immune nucleases (poxins) from the 2′,3′-cGAMP-degrading enzyme family.

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MARCENIUK, ALEXANDRE PIRES, RODRIGO ANTUNES CAIRES, LEONARDO MACHADO, NAJILA NOLIE CATARINE DANTAS CERQUEIRA, RAYLA ROBERTA M. DE S. SERRA et CLAUDIO OLIVEIRA. « Redescription of Orthopristis ruber and Orthopristis scapularis (Haemulidae : Perciformes), with a hybridization zone off the Atlantic coast of South America ». Zootaxa 4576, n^o 1 (1 avril 2019) : 109. http://dx.doi.org/10.11646/zootaxa.4576.1.5.

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The genus Orthopristis includes seven valid species, three from the western Atlantic and five from eastern Pacific, while the available identification guides and taxonomic keys incorrectly recognize Orthopristis ruber as the only valid species found on the Atlantic coast of South America. Efforts to expand the inventory of fish species from the northern coast of Brazil led to the identification of two distinct species of Orthopristis from Atlantic South America, based on the analysis of coloration patterns and meristic data, as well as DNA. In the present study, the limits of Orthopristis ruber are reviewed, while Orthopristis scapularis is recognized as a valid species for the northern and northeastern coasts of South America. Based on intermediate morphological characteristics and nuclear DNA markers, a hybrid zone was identified off the state of Espírito Santo, on the eastern Brazilian coast. Additionally, considerations are made on the diversity and biogeography of the coastal marine and estuarine fishes found on the Brazilian coast.

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Komura, Motonori, Ken Nakajima, Toshio Nishi, Takayuki Ikehara et Qiu Zhaobin. « Pulsed NMR Studies on Long-Term Crystallization Behavior and Melting Process of Natural Rubber under Elongation ». Rubber Chemistry and Technology 81, n^o 1 (1 mars 2008) : 110–20. http://dx.doi.org/10.5254/1.3548191.

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Abstract Long-term crystallization and melting process of natural rubber under elongation was investigated by measuring spin-spin relaxation time T2 by pulsed nuclear magnetic resonance (NMR). We examined the dependence of the both processes on extension ratio, crystallization temperature and crosslink density. It was found that the crystallization of natural rubber continued over three months even at 10 °C. According to the two-step melting process found for the first time under elongation, we proposed a model that crystalline part of natural rubber under large elongation is composed of two kinds of crystallites from highly extended and loose chains. The situation is caused by the microscopic distribution of extension ratio of the chains between crosslink points.

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Chen, Chi-Yao, Zih-Yao Shen et Maw-Tien Lee. « On Developing a Hydrophobic Rubberized Cement Paste ». Materials 14, n^o 13 (1 juillet 2021) : 3687. http://dx.doi.org/10.3390/ma14133687.

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It is well known that most cement matrix materials are hydrophilic. For structural materials, hydrophilicity is harmful because the absorption of water will induce serious damage to these materials. In this study, crumb rubber was pretreated by partial oxidation and used as an additive to develop a hydrophobic rubberized cement paste. The pretreated crumb rubber was investigated using Fourier-transform infrared spectrometry (FT-IR) to understand the function groups on its surface. The pyrolysis oil adsorbed on the surface of the crumb rubber was observed by FT-IR and nuclear magnetic resonance (NMR) spectroscopy. A colloid probe with calcium silicate hydrate (C–S–H) at the apex was prepared to measure the intermolecular interaction forces between the crumb rubber and the C-S-H using an atomic force microscope (AFM). Pure cement paste, cement paste with the as-received crumb rubber, and cement paste with pretreated crumb rubber were prepared for comparison. FT-IR, X-ray diffraction (XRD), and scanning electron microscopy (SEM) were used to understand the microstructure of the pastes. The static contact angle was used as the index of the hydrophobicity of the pastes. Experimental results showed that the hardened cement paste containing partially oxidized crumb rubber had excellent hydrophobic properties with an insignificant reduction in the compressive strength.

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Trejo-Machin, Acerina, João Paulo Cosas Fernandes, Laura Puchot, Suzanne Balko, Marcel Wirtz, Marc Weydert et Pierre Verge. « Synthesis of Novel Benzoxazines Containing Sulfur and Their Application in Rubber Compounds ». Polymers 13, n^o 8 (13 avril 2021) : 1262. http://dx.doi.org/10.3390/polym13081262.

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This work reports the synthesis and successful use of novel benzoxazines as reinforcing resins in polyisoprene rubber compounds. For this purpose, three new dibenzoxazines containing one (4DTP-fa) or two heteroatoms of sulfur (3DPDS-fa and 4DPDS-fa) were synthesized following a Mannich condensation reaction. The structural features of each benzoxazine precursor were characterized by 1H and 13C nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) and Raman. The new precursors showed well suited reactivity as characterized by differential scanning calorimetry (DSC) and rheology and were incorporated in rubber compounds. After the mixing, the curing profiles, morphologies and mechanical properties of the materials were tested. These results show that the structural feature of each isomer was significantly affecting its behavior during the curing of the rubber compounds. Among the tested benzoxazines, 3DPDS-fa exhibited the best ability to reinforce the rubber compound even compared to common phenolic resin. These results prove the feasibility to reinforce rubber compounds with benzoxazine resins as a possible alternative to replace conventional phenolic resins. This paper provides the first guide to use benzoxazines as reinforcing resins for rubber applications, based on their curing kinetics.

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Moolsin, Supat, Nattawud Saksayamkul et Adul Na Wichien. « Natural rubber grafted poly(methyl methacrylate) as compatibilizer in 50/50 natural rubber/nitrile rubber blend ». Journal of Elastomers & ; Plastics 49, n^o 5 (7 octobre 2016) : 422–39. http://dx.doi.org/10.1177/0095244316671021.

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The effects of graft copolymers applied as compatibilizers for natural rubber/nitrile rubber (NR/NBR) blends at 50/50 (w/w) on cure characteristics, mechanical properties, thermal properties, oil resistance, and morphology were investigated. The graft copolymers of methyl methacrylate (MMA) onto NR initiated by benzoyl peroxide (NR- g-PMMA<BPO>) and by potassium persulfate (NR- g-PMMA<PPS>) under emulsion polymerization were synthesized and used to compatibilize the blends. The structures of the copolymers were characterized by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy. NR was blended with NBR via a two-roll mill at 70°C under the compatibilizer loading ranging from 0 to 10 parts per hundred of rubber (phr). The results showed that the tensile property and tear strength of the blends increased with the increasing amount of NR- g-PMMA<BPO> as a compatibilizer. Thermal aging determined in terms of tensile properties exhibited the smaller difference between before and after aging in an oven with the increasing compatibilizer loading. The morphology of the compatibilized NR/NBR vulcanizates was investigated by scanning electron microscopy of the tensile fracture surfaces, which exhibited the improvement of interfacial adhesion between the two rubber phases. The thermal properties of compatibilized NR/NBR vulcanizates were reported in terms of a glass transition temperature under differential scanning calorimetry and dynamic mechanical analysis. The incorporation of an appropriate amount of the compatibilizer into the blends apparently improved the oil resistance of NR. Among them, the blend filled with 7.5 phr of NR- g-PMMA<BPO> showed the lowest volume change in IRM 903 oil.

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Cobani, Elkid, Irene Tagliaro, Marco Geppi, Luca Giannini, Philippe Leclère, Francesca Martini, Thai Nguyen et al. « Hybrid Interface in Sepiolite Rubber Nanocomposites : Role of Self-Assembled Nanostructure in Controlling Dissipative Phenomena ». Nanomaterials 9, n^o 4 (27 mars 2019) : 486. http://dx.doi.org/10.3390/nano9040486.

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Sepiolite (Sep)–styrene butadiene rubber (SBR) nanocomposites were prepared by using nano-sized sepiolite (NS-SepS9) fibers, obtained by applying a controlled surface acid treatment, also in the presence of a silane coupling agent (NS-SilSepS9). Sep/SBR nanocomposites were used as a model to study the influence of the modified sepiolite filler on the formation of immobilized rubber at the clay-rubber interface and the role of a self-assembled nanostructure in tuning the mechanical properties. A detailed investigation at the macro and nanoscale of such self-assembled structures was performed in terms of the organization and networking of Sep fibers in the rubber matrix, the nature of both the filler–filler and filler–rubber interactions, and the impact of these features on the reduced dissipative phenomena. An integrated multi-technique approach, based on dynamic measurements, nuclear magnetic resonance analysis, and morphological investigation, assessed that the macroscopic mechanical properties of clay nanocomposites can be remarkably enhanced by self-assembled filler structures, whose formation can be favored by manipulating the chemistry at the hybrid interfaces between the clay particles and the polymers.

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Li, Yan, Wencai Yu, Yueyi Chen, Shuguang Yang, Shaohua Wu, Jinquan Chao, Xinlong Wang et Wei-Min Tian. « Genome-Wide Identification and Characterization of Heat-Shock Transcription Factors in Rubber Tree ». Forests 10, n^o 12 (17 décembre 2019) : 1157. http://dx.doi.org/10.3390/f10121157.

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Heat-shock transcription factors (Hsfs) play a pivotal role in the response of plants to various stresses. The present study aimed to characterize the Hsf genes in the rubber tree, a primary global source of natural rubber. In this study, 30 Hsf genes were identified in the rubber tree using genome-wide analysis. They possessed a structurally conserved DNA-binding domain and an oligomerization domain. On the basis of the length of the insert region between HR-A and HR-B in the oligomerization domain, the 30 members were clustered into three classes, Classes A (18), B (10), and C (2). Members within the same class shared highly conserved gene structures and protein motifs. The background expression levels of 11 genes in cold-tolerant rubber-tree clone 93-14 were significantly higher than those in cold-sensitive rubber-tree clone Reken501, while four genes exhibited inverse expression patterns. Upon cold stress, 20 genes were significantly upregulated in 93-114. Of the upregulated genes, HbHsfA2b, HbHsfA3a, and HbHsfA7a were also significantly upregulated in three other cold-tolerant rubber-tree clones at one or more time intervals upon cold stress. Their nuclear localization was verified, and the protein–protein interaction network was predicted. This study provides a basis for dissecting Hsf function in the enhanced cold tolerance of the rubber tree.

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Chen, Yu, Yang Zhang, Yuchuan Wang, Liguo Zhang, Eva K. Brinkman, Stephen A. Adam, Robert Goldman, Bas van Steensel, Jian Ma et Andrew S. Belmont. « Mapping 3D genome organization relative to nuclear compartments using TSA-Seq as a cytological ruler ». Journal of Cell Biology 217, n^o 11 (28 août 2018) : 4025–48. http://dx.doi.org/10.1083/jcb.201807108.

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While nuclear compartmentalization is an essential feature of three-dimensional genome organization, no genomic method exists for measuring chromosome distances to defined nuclear structures. In this study, we describe TSA-Seq, a new mapping method capable of providing a “cytological ruler” for estimating mean chromosomal distances from nuclear speckles genome-wide and for predicting several Mbp chromosome trajectories between nuclear compartments without sophisticated computational modeling. Ensemble-averaged results in K562 cells reveal a clear nuclear lamina to speckle axis correlated with a striking spatial gradient in genome activity. This gradient represents a convolution of multiple spatially separated nuclear domains including two types of transcription “hot zones.” Transcription hot zones protruding furthest into the nuclear interior and positioning deterministically very close to nuclear speckles have higher numbers of total genes, the most highly expressed genes, housekeeping genes, genes with low transcriptional pausing, and super-enhancers. Our results demonstrate the capability of TSA-Seq for genome-wide mapping of nuclear structure and suggest a new model for spatial organization of transcription and gene expression.

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Nobari Azar, Farzad A., et Murat Şen. « Effects of accelerator type on stress relaxation behavior and network structure of aged natural rubber/chloroprene rubber vulcanizates ». Journal of Elastomers & ; Plastics 49, n^o 5 (18 août 2016) : 381–96. http://dx.doi.org/10.1177/0095244316663268.

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Natural rubber/chloroprene rubber (NR/CR) blends are among the commonly used rubber blends in industry and continuously are exposed to severe weather changes. To investigate the effects of accelerator type on the network structure and stress relaxation of unaged and aged NR/CE vulcanizates, tetramethyl thiuram disulfide, 2-mercaptobenzothiazole, and diphenyl guanidine accelerators have been chosen to represent fast, moderate, and slow accelerator groups, respectively. Three batches have been prepared with exactly the same components and mixing conditions differing only in accelerator type. Temperatures scanning stress relaxation and pulse nuclear magnetic resonance techniques have been used to reveal the structural changes of differently accelerated rubber blends before and after weathering. Nonoxidative thermal decomposition analyses have been carried out using a thermogravimetric analyzer. Results indicate that there is a strong interdependence between accelerator type and stress relaxation behavior, network structure, cross-linking density, and aging behavior of the blends. Accelerator type also affects decomposition energy of the blends.

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Walsh, Neil G., James K. Hardy et Peter L. Rinaldi. « Use of 13C Nuclear Magnetic Resonance Spectroscopy and Principal Component Analysis for Automated Analysis of Styrene/Butadiene Copolymers ». Applied Spectroscopy 51, n^o 6 (juin 1997) : 889–97. http://dx.doi.org/10.1366/0003702971941205.

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Principal component analysis (PCA) is used here to determine percent composition of the four monomer units styrene, 1,2-butadiene (vinyl), trans-1,4-butadiene ( trans), and cis-1,4-butadiene ( cis) in styrene/butadiene rubber (SBR) copolymers and the three monomer units (vinyl, trans, and cis) in butadiene rubber (BR) polymers. Comparison of PCA with current methods is described. Cluster analysis is used to classify the SBR and BR into groups.

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Ramachandran, P., S. Mathur, L. Francis, A. Varma, J. Mathew, N. M. Mathew et M. R. Sethuraj. « Evidence for Association of a Viroid with Tapping Panel Dryness Syndrome of Rubber (Hevea brasiliensis) ». Plant Disease 84, n^o 10 (octobre 2000) : 1155. http://dx.doi.org/10.1094/pdis.2000.84.10.1155c.

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Tapping panel dryness (TPD) is one of the most destructive maladies affecting rubber plantations and is becoming a matter of serious concern. Reduced latex yield leading to total drying of the tapping panel is the obvious symptom. The cause of TPD syndrome is unknown but has been mostly attributed to abiotic causes. In India, the high yielding commercial clone RRII 105 is affected by TPD, leading to enormous losses. We have observed that TPD-affected trees show symptoms of bark scaling, cracking, drying, necrotic streaking, and browning of internal bark leading to the decay of internal tissues. Often prominent abnormal bulges on the lower part of tree trunks occur where the first panel begins to dry. Investigations on TPD-affected rubber samples did not reveal the association of fungus, bacterium, virus, or a protozoan. Total nucleic acid extracts purified from leaf and bark tissues of affected samples and analyzed by polyacrylamide gel electrophoresis under denaturing conditions of low salt and high temperature showed the presence of nucleic acids similar in electrophoretic mobility to low molecular weight (LMW) RNA, of ~359 nucleotides such as potato spindle tuber viroid (PSTVd). The LMW nucleic acid detected from TPD-affected samples was found to be RNA based on its sensitivity to RNase and insensitivity to DNase, phenol, and heat treatments. The LMW RNA was purified and cloned in a pUC 19-derived vector by using primers specific to PSTVd (1). The cloned DNA, when random labeled and used as probe reacted specifically to nucleic acid extracts from TPD-affected rubber trees but not from healthy tissue in dot-blot hybridization assays. Based on the above findings, a viroid etiology for TPD syndrome is proposed. Reference: (1) R. A. Owens, A. T. Candresse, and T. O. Diener. Virology 175:238, 1990.

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Valentín, J. L., R. Pérez-Aparicio, A. Fernandez-Torres, P. Posadas, R. Herrero, F. M. Salamanca, R. Navarro et L. Saiz-Rodríguez. « ADVANCED CHARACTERIZATION OF RECYCLED RUBBER FROM END-OF-LIFE TIRES ». Rubber Chemistry and Technology 93, n^o 4 (1 octobre 2020) : 683–703. http://dx.doi.org/10.5254/rct.20.79963.

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ABSTRACT There are currently many well-established applications for recycled rubber from end-of-life tires (ELT), but it is essential to investigate and seek new approaches to enhance the value of these products. Recent developments in new technologies and innovative recycling and devulcanization processes have opened up new perspectives for ELT crumb rubber. To promote the use of these products in newly added value applications, it is essential to develop and optimize methods that allow the characterization of parameters related to the ultimate properties of potential final applications. In this respect, a novel characterization methodology based on advanced 1H double-quantum (DQ) nuclear magnetic resonance experiments has been applied for the first time to quantify the key parameters that characterize the structure of ELT crumb rubber after diverse recycling processes: from simple mechanical grinding to complex devulcanization methods. This experimental approach enables the quantification of parameters that define the network structure of rubber, such as the nonelastic network defects (sol fraction, dangling chain ends, loops), the cross-link density, and the heterogeneity of the network, directly from rubber granulate and powder (without any additional sample preparation steps), overcoming most of the drawbacks and uncertainties that limit the application of traditional rubber characterization methods (e.g., equilibrium swelling experiments). By applying this experimental approach, it is possible to identify and quantify the actual technical limits for a complete selective devulcanization process of ELT crumb rubber.

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Ning, Bo, Jun-Wen Cao, Xiao-Teng Zhou, He Qin, Ling-Xiao Li et Cheng-You Kan. « Synthesis and characterization of a novel, reactive, yellow fluorescent organosilicon dye and its polysiloxanes ». Journal of Chemical Research 43, n^o 11-12 (30 août 2019) : 461–68. http://dx.doi.org/10.1177/1747519819872098.

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A novel, reactive, yellow fluorescent organosilicon dye, N-propyl-(diethoxy)methyl-silane-4-dimethylamino-naphthalimide, is designed and synthesized and is used to fabricate a covalently yellow fluorescent silicone oil by polycondensation of hydroxy-terminated polydimethylsiloxane. The chemical structure and optical properties of the N-propyl-(diethoxy)methyl-silane-4-dimethylamino-naphthalimide and covalently yellow fluorescent silicone oil are characterized by 1H nuclear magnetic resonance, 13C nuclear magnetic resonance, mass spectrometry, Fourier transform infrared, UV–Vis, and fluorescence spectra. The results indicate that the fluorescence quantum yields of N-propyl-(diethoxy)methyl-silane-4-dimethylamino-naphthalimide and covalently yellow fluorescent silicone oil are 2.61% and 3.5%, respectively. The λmax values of their dichloromethane solutions are 416 nm, and their λex and λem are 430 and 509 nm, respectively. Furthermore, covalently yellow fluorescent silicone rubbers are prepared using tetraethoxysilane as a cross-linker, and some of their properties are investigated. Thermogravimetric analysis and dynamic mechanical analysis show that heat resistance and tan δ of the covalently yellow fluorescent silicone rubber are improved in comparison with silicone rubbers without N-propyl-(diethoxy)methyl-silane-4-dimethylamino-naphthalimide moieties. Solvent extraction experiments indicate that the solvent resistance of the covalently yellow fluorescent silicone rubber is much better than that of noncovalently yellow fluorescent silicone rubber.

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Corcelli, Angela, Veronica M. T. Lattanzio, Giuseppe Mascolo, Francesco Babudri, Aharon Oren et Morris Kates. « Novel Sulfonolipid in the Extremely Halophilic Bacterium Salinibacter ruber ». Applied and Environmental Microbiology 70, n^o 11 (novembre 2004) : 6678–85. http://dx.doi.org/10.1128/aem.70.11.6678-6685.2004.

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ABSTRACT Salinibacter ruber is an extremely halophilic bacterium, phylogenetically affiliated with the Flavobacterium/Cytophaga branch of the domain Bacteria. Electrospray mass analyses (negative ion) of the total lipid extract of a pure culture of S. ruber shows a characteristic peak at m/z 660 as the most prominent peak in the high-mass range of the spectrum. A novel sulfonolipid, giving rise to the molecular ion [M-H]− of m/z 660, has been identified. The sulfonolipid isolated and purified by thin-layer chromatography was shown by chemical degradation, mass spectrometry, infrared spectroscopy, and nuclear magnetic resonance analysis to have the structure 2-carboxy-2-amino-3-O-(13′-methyltetradecanoyl)-4-hydroxy-18-methylnonadec-5-ene-1-sulfonic acid. This lipid represents about 10% of total cellular lipids, and it appears to be a structural variant of the sulfonolipids found as main components of the cell envelope of gliding bacteria of the genus Cytophaga and closely related genera (W. Godchaux and E. R. Leadbetter, J. Bacteriol. 153:1238-1246, 1983) and of diatoms (R. Anderson, M. Kates, and B. E. Volcani, Biochim. Biophys. Acta 528:89-106, 1978). Since this sulfonolipid has never been observed in any other extreme halophilic microorganism, we consider the peak at m/z 660 the lipid signature of Salinibacter. This study suggests that this novel sulfonolipid may be used as a chemotaxonomic marker for the detection of Salinibacter within the halophilic microbial community in saltern crystallizer ponds and other hypersaline environments.

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Chang, Yuan-Shang, et Ali Mosleh. « Probabilistic model of degradation of cable insulations in nuclear power plants ». Proceedings of the Institution of Mechanical Engineers, Part O : Journal of Risk and Reliability 233, n^o 5 (15 février 2019) : 803–14. http://dx.doi.org/10.1177/1748006x19827127.

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Possible degradation of cable insulations exposed to radiation and heat is a safety and operational concern for nuclear power plants, particularly in the context of a license extension for the operation beyond original 40-year design life. Ethylene propylene rubber and silicone rubber are two major materials for the cable insulation. Degradation decreases the elongation at break of the insulation, which may lead to the exposure of the metal core in the cable, causing potential safety issues. This article proposes a mechanistic predictive model for the elongation at break as a function of time, temperature, and radiation dose rate. In the proposed model, the elongation at break curve is divided into an incubation section and a drop-off section with two parameters. In contrast to traditional deterministic approaches, this model projects the expected lifespan of cable insulation in the form of a probability distribution. The article also provides a validation of the model behavior using published experimental data.

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Liu, Chaohao, Mingming Guo, Xiaobo Zhai, Xin Ye et Liqun Zhang. « Using Epoxidized Solution Polymerized Styrene-Butadiene Rubbers (ESSBRs) as Coupling Agents to Modify Silica without Volatile Organic Compounds ». Polymers 12, n^o 6 (30 mai 2020) : 1257. http://dx.doi.org/10.3390/polym12061257.

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Rubber used in tire is usually strengthened by nanofiller, and the most popular nanofiller for tire tread rubber is nano silica, which can not only strengthen rubber but also lower the tire rolling resistance to reduce fuel consumption. However, silica particles are difficult to disperse in the rubber matrix because of the abundant silicon hydroxyl on their surface. Silane coupling agents are always used to modify silica and improve their dispersion, but a large number of volatile organic compounds (VOCs) are emitted during the manufacturing of the nanosilica/rubber composites because of the condensation reaction between silane coupling agents and silicon hydroxyl on the surface of silica. Those VOCs will do great harm to the environment and the workers’ health. In this work, epoxidized solution polymerized styrene-butadiene rubbers (ESSBR) with different epoxy degrees were prepared and used as macromolecular coupling agents aimed at fully eliminating VOCs. Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) analyses verified that the different ESSBRs were successfully synthesized from solution polymerized styrene-butadiene rubbers (SSBR). With the help of the reaction between epoxy groups and silicon hydroxyl without any VOC emission, nanosilica can be well dispersed in the rubber matrix when SSBR partially replaced by ESSBR which was proved by Payne effect and TEM analysis. Dynamic and static mechanical testing demonstrated that silica/ESSBR/SSBR/BR nanocomposites have better performance and no VOC emission compared with Bis-(γ-triethoxysilylpropyl)-disulfide (TESPD) modified silica/rubber nanocomposites. ESSBR is very hopeful to replace traditional coupling agent TESPD to get high properties silica/rubber nanocomposites with no VOCs emission.

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Dong, Z. P., B. J. Cauley, A. Bandis, C. W. Mou, C. E. Inglefield, A. A. Jones, P. T. Inglefield et W. Y. Wen. « Nuclear spin relaxation dynamics of 13CO2 sorbed in polyisobutene rubber ». Journal of Polymer Science Part B : Polymer Physics 31, n^o 9 (août 1993) : 1213–21. http://dx.doi.org/10.1002/polb.1993.090310916.

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He, Min, Qiu Yu Zhang et Ji Ying Guo. « Synthesis and Characterization of Silicone Based Pressure Sensitive Adhesive ». Advanced Materials Research 306-307 (août 2011) : 1773–78. http://dx.doi.org/10.4028/www.scientific.net/amr.306-307.1773.

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The MQ silicone resin was synthesized by using chlorotrimethylsilane and tetraethyl orthosilicate and its structure was analyzed by means of Fourier transform infrared spectroscopy, 29Si-nuclear magnetic resonance and gel permeation chromatography. The silicone based pressure sensitive adhesive was obtained by condensation polymerization between the MQ resin and methyl silicone rubber terminated with hydroxyl group. The structure of the adhesive was characterized by FTIR, and its thermal properties were investigated via thermogravimetic analysis. The results show that the MQ resin successfully had a condensation polymerization reaction with the silicone rubber. The pressure sensitive adhesive had excellent tack, peel strength and high temperature resistance properties.

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Zhang, Wenzheng, Ning Jiang et Tingting Zhang. « Self-plasticization of neoprene rubber via click chemistry from environmentally sustainable cardanol ». Journal of Elastomers & ; Plastics 52, n^o 6 (26 août 2019) : 483–94. http://dx.doi.org/10.1177/0095244319869768.

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The sustainable biomass cardanol grafting onto neoprene (CR) rubber was carried out successfully at room temperature by covalently binding to CR via click chemistry to realize the internal plasticization of CR rubber. The structure of the synthesized product was characterized by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance, and differential scanning calorimetry and thermogravimetric analysis demonstrate a lowering of the glass transition temperature of the CR-propargyl ether cardanol as compared to CR. This confirms the plasticization effect of the cardanol when grafted onto CR. The cardanol as an internal plasticizer also has a good thermal stability and almost near-zero migration.

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Hayichelaeh, C., L. A. E. M. Reuvekamp, W. K. Dierkes, A. Blume, J. W. M. Noordermeer et K. Sahakaro. « SILICA-REINFORCED NATURAL RUBBER TIRE TREAD COMPOUNDS CONTAINING BIO-BASED PROCESS OILS. II : INFLUENCE OF EPOXIDE AND AMINO FUNCTIONAL GROUPS ». Rubber Chemistry and Technology 93, n^o 1 (1 janvier 2020) : 195–207. http://dx.doi.org/10.5254/rct.19.81461.

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ABSTRACT The feasibility of the use of epoxidized palm oil (EPO) and amine-modified epoxidized palm oil (mEPO) as process oils in silica-reinforced natural rubber compounds is studied. The chemical structures of EPO and mEPO are characterized by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy (1H-NMR). Amine modification for 3 and 5 h leads to mEPOs with 0.03 and 0.04 mmol of amine in 1 g of oil, referred to as 0.03 mEPO and 0.04 mEPO, respectively. The properties of rubber compounds containing modified palm oils are investigated by taking those with TDAE oil and those without oil as references. The use of process oils clearly enhances the processibility (i.e., lower mixing torque and complex viscosity) and mechanical and dynamic mechanical properties of the rubber compounds as compared with compounds without oil. The rubber compounds with EPO and 0.03 mEPO show a lower Payne effect (i.e., less filler–filler interaction) than the rubber compound with TDAE because of the shielding effect of the oils on the silica surface. The use of mEPO boosts the vulcanization reaction, resulting in much better cure torque difference, which indicates a higher crosslink density due to the amino groups present in mEPO as compared with TDAE. Therefore, rubber compounds with mEPOs have better mechanical properties (i.e., reinforcement index, tensile strength, and elongation at break) and better elastic response under dynamic deformation, as indicated by a lower loss tangent at 60 °C as compared with the mix with TDAE.

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Onchoy, Nuchanart, et Pranee Phinyocheep. « PREPARATION AND CHARACTERIZATION OF BROMINATED NATURAL RUBBER APPLIED IN SILICA-FILLED NATURAL RUBBER VULCANIZATES ». Rubber Chemistry and Technology 89, n^o 3 (1 septembre 2016) : 406–18. http://dx.doi.org/10.5254/rct.16.84833.

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ABSTRACT Functionalization of NR with a bromine atom was developed and explored for its application in a silica-reinforced NR system. Two possible pathways were investigated: the direct addition of a bromine atom using N-bromosuccinimide (NBS) with FeCl2 as a catalyst in the latex phase (NR–Br); and an indirect method using a ring opening of epoxidized natural rubber (ENR) with 2-bromopropionic acid (ENR–Br). The chemical structure, including determination of the bromine contents, was analyzed with proton nuclear magnetic resonance and Fourier transform infrared spectroscopy. The occurrence of bromine in NR–Br was confirmed using scanning electron microscopy with energy dispersive x-ray spectroscopy. Strong emission peaks for Br Kα at 1.5 eV was evidenced. Moreover, glass transition temperature of modified NRs increased after bromination. Two types of brominated NR, that is, NR–Br and ENR–Br containing 2 and 4 mol% of bromine function, respectively, were used in a range of 1–5 phr in the silica-reinforced NR system with silica loading of 10 and 30 phr. Both cure and mechanical properties of the rubber compounds were investigated. The incorporation of the bromine function in NR of both ENR–Br and NR–Br enhanced the cure reactivity of the NR–silica vulcanization system. The modified NRs may have a role as a coupling agent between the NR and the silica filler.

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