The photolytic stability of various RAFT agents (i.e., thiocarbonylthio-containing compounds) under irradiation from a blue LED light source has been investigated. The effect and implications of efficient photo-fragmentation and potential photo-degradation with regard to their performance in photopolymerization reactions is reported. The stability is found to depend strongly on the structure of the fragmenting (R-) group and the reactivity of the carbon-centered radical formed following photolytic cleavage. This is proposed to be due to the competitive rates of radical recombination and thiyl radical degradation, and has implications on the choice of monomer (as monomer propagation requires reinitiation of the oligomeric/polymeric RAFT agent). These findings can provide guidelines and increase understanding when conducting a photopolymerization employing thiocarbonylthio RAFT agents. † Electronic supplementary information (ESI) available: Materials and characterization details. Experimental procedures and supplementary figures. See
Abstract. An analysis of testicular morphology and spermatogenesis in the Heteroptera species Antiteuchus tripterus (Pentatomidae) revealed that these traits differ from that recorded for other species of the same family. The testes of A. tripterus have only six lobes, while other species of the same family typically have seven lobes, including a compound lobe, i.e., a lobe containing another in its lumen. A study of meiosis and sperm structure in the different lobes of A. tripterus revealed a conventional meiosis in the lobes numbered one to three. In lobe four, however, prophase I spermatocytes exhibit the morphological characteristics of the so called "diffuse" stage and are larger than those in lobes 1-3 in this and the remaining phases of meiosis. Thus, the resulting spermatids are not only larger but also their head is morphologically different. Lobe 5 exhibits characteristics known from other Pentatomidae species such as an uneven distribution of chromatin to the daughter cells, which give rise to cells of different sizes. This lobe forms spermatozoa of different sizes. Lobe 6, contained within lobe 5, differs from it by having larger cells at a stage similar to the so called "diffuse" and spermatid tails with cross divisions, which are not found in other lobes and unreported in the literature.
ABStrACt. Males of Limnogonus aduncus were found to have the sex chromosome system X0 and chromosome number 2n = 23 (22A + X0). Testis cells were stained with lacto-acetic orcein and silver nitrate so that changes in the morphology and degree of staining of the heteropicnotic chromatin and the nucleolar material could be observed during meiosis and spermiogenesis. These structures share the same nuclear position and could be seen until almost the end of spermiogenesis. A chromosome region stained with silver ni-
Summary Some cytogenetical aspects of spermatozoa formation were studied in 9 Coreidae Brazilian species: Anasa bellator, Athaumastus haematicus, Chariesterus armatus, Dallacoris obscura, Dallacoris pictus, Leptoglossus gonagra, Leptoglossus zonatus, Sphictyrtus fasciatus, and Zicca annulata. Similarly to the other species described to date, all the species studied herein showed cystic spermatogenesis, a reddish membrane covering the testes, a X0 sex determining system, a pair of m-chromosomes, intersticial chiasmata in most autosomes, and autosomes dividing reductionally at first meiotic division and equationally in the second 1 while sex chromosomes, divide equationally and reductionally at first and second meiotic division, respectively. In addition, it was observed that the sex chromosome is heteropycnotic at prophase and that heteropycnotic chromosomal material is found in the nuclei at spermiogenesis. In the species studied, the diploid chromosome number ranged from 19 to 25. It was 19 in S. fasciatus (16Aϩ2mϩX0); 21 in A. bellator, A. haematicus, D. obscura, D. pictus, L. gonagra, and L. zonatus (18Aϩ2mϩX0); 23 in Z. annulata (20Aϩ2mϩX0); and 25 in C. armatus (22Aϩ2mϩX0).
ABSfRAcr. NEOTROPICAL MIRIDAE. CCCXCVIII. NEW GENUS ANO SPECIES FROM SOUTH OF BRAZIL (HEMIPTERA). A new genus and five new species of Hemiptera, Miridae, from south of Brazil are described as follows: DerophthaIma vittinotata, sp.n.; Parachius paIlidus, sp.n.; Paranacoris, gen.n.; Paranacoris vertexaIbus, sp.n.; Tropidosteptes viUiscuteIlatus, sp.n.; Tupiniqui. nus aIboantennatus, sp.n. IIIustrations of habitus and male genitalia are included.
Plastic production has been increasing at enormous rates. Particularly, the socioenvironmental problems resulting from the linear economy model have been widely discussed, especially regarding plastic pieces intended for single use and disposed improperly in the environment. Nonetheless, greenhouse gas emissions caused by inappropriate disposal or recycling and by the many production stages have not been discussed thoroughly. Regarding the manufacturing processes, carbon dioxide is produced mainly through heating of process streams and intrinsic chemical transformations, explaining why first-generation petrochemical industries are among the top five most greenhouse gas (GHG)-polluting businesses. Consequently, the plastics market must pursue full integration with the circular economy approach, promoting the simultaneous recycling of plastic wastes and sequestration and reuse of CO2 through carbon capture and utilization (CCU) strategies, which can be employed for the manufacture of olefins (among other process streams) and reduction of fossil-fuel demands and environmental impacts. Considering the previous remarks, the present manuscript’s purpose is to provide a review regarding CO2 emissions, capture, and utilization in the plastics industry. A detailed bibliometric review of both the scientific and the patent literature available is presented, including the description of key players and critical discussions and suggestions about the main technologies. As shown throughout the text, the number of documents has grown steadily, illustrating the increasing importance of CCU strategies in the field of plastics manufacture.
Pyrolysis is a chemical recycling technology that is experiencing fast development, is complementary to mechanical recycling, and is used to avoid incorrect disposal of postconsumer plastics (mainly polyolefins) and decrease environmental impacts related to the production of virgin plastic. However, although it has been widely accepted that pyrolysis can constitute an essential technology for the present and the future, discussions regarding the increase of scale, process sustainability, and other aspects needed for the circular economy must be carried out more thoroughly. For this reason, in this work, life cycle assessments (LCAs) of pyrolytic processes are discussed, showing that available LCA studies still lack holistic consistency and representativeness, based on a short review of previously published studies and proposed approaches and limitations.
Pentatomidae is a family of Heteroptera which includes several agriculture pests that have had different aspects of their meiosis and spermiogenesis analyzed. In the present study we analyzed the morphological patterns of the heteropycnotic chromatin and the nucleolar material of Mormidea v-luteum, Oebalus poecilus and Oebalus ypsilongriseus. The three species presented multilobate testes, with three lobes in M. v-luteum and four in the Oebalus species. A karyotype with 2n = 14 chromosomes (12A + XY) was observed in the three species. Several characteristics were common to the three species, such as the absence of a testicular harlequin lobe (a lobe which produces different types of spermatozoa, previously considered a general characteristic of this family), late migration of the sex chromosomes and semi-persistence of the nucleolus. The three species also shared some characteristics regarding the patterns of the heteropycnotic chromatin and nucleolar material, but differed in others mainly related to the location of the heteropycnotic chromatin in the spermatids and the morphology and distribution of the nucleolar material at zygotene. The differences were always between species from different genera, suggesting a relationship with their genetic divergence.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.