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Anodic Cyclizations, Seven-Membered Rings, and the Choice of Radical Cation *** Pathways

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Chinese journal of Chemistry 2019年第7期37卷 672-678页

作者： robert j.Perkins Ruozhu Feng Qingquan Lu Kevin D.Moeller Department of Chemistry Washington University in St.Louis St.Louis MO 63130 USA

While many steps in an oxidative cyclization reaction can be important,it is the cyclization step itself that plays the central *** this step does not proceed well,then optimization of the rest of the sequence is *** report here that the key to the cyclization is channeling the reaction down the correct *** reactions require the use of a radical pathway and some require the use of a radical cation *** example of each is provided along with a strategy for accessing both pathways using a common intermediate.

关键词： Anodic Cyclizations Seven-Membered Rings

Granular titanite from the Roter Kamm crater in Namibia:Product of regional metamorphism,not meteorite impact

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Geoscience Frontiers 2022年第3期13卷 156-163页

作者： Aaron j.Cavosie Christopher j.Spencer Noreen Evans Kai Rankenburg robert j.Thomas Paul H.Macey Space Science and Technology Centre and The Institute for Geoscience Research School of Earth and Planetary ScienceCurtin UniversityPerthWA 6102Australia Dept.of Geological Sciences and Geological Engineering Queen’s UniversityOntarioCanada john de Laeter Centre Curtin UniversityPerthWA 6102Australia Council for Geoscience BellvilleWestern CapeSouth Africa

Accessory minerals with so-called granular texture have risen in importance as geochronological tools for U-Pb dating of meteorite impact events. Grain-scale recrystallization, typically triggered by a combination of high-strain deformation and post-impact heating, can create a polycrystalline microstructure consisting of neoblasts that expel radiogenic Pb, which are thus ideal for isotopic dating. While granular domains in zircon and monazite from shocked rocks have been demonstrated to preserve impact ages,few U-Pb dating studies have been conducted on granular microstructures in titanite(CaTiSiO;). Here we report the occurrence of granular-textured titanite from ~2020 Ma granite basement rock exposed in the rim of the 4–5 Ma Roter Kamm impact structure in Namibia. Orientation mapping reveals two microstructurally distinct titanite populations: one consisting of strained/deformed grains, and the other consisting of grains that comprise aggregates of strain-free neoblasts. In situ U-Pb geochronology on 37 grains shows that most grains from both titanite populations yield indistinguishable U-Pb dates of ca.1025 Ma, consistent with the observed microstructures forming during the Mesoproterozoic Namaqua Orogeny. Only four grains preserved older age domains, recording ca. 1875 Ma Paleoproterozoic metamorphism. Two significant observations emerge:(1) none of the analyzed titanite grains yield the 2020 Ma igneous crystallization age previously established from zircon in the same sample, and(2) no age-resetting was detected that could be attributed to the 4 to 5 Ma Roter Kamm impact *** the similarity of the neoblastic microstructure to minerals from other sites with an established impact provenance, the granular texture and near-complete Pb-loss in titanite from Roter Kamm granite instead records a Paleo-to Mesoproterozoic polymetamorphic history, rather than Miocene age shockrelated processes. These results highlight the critical importance of grain-scale cont

关键词： Namibia Roter Kamm Titanite EBSD Geochronology

Recurrence and survival following microwave, radiofrequency ablation, and hepatic resection of colorectal liver metastases: A systematic review and network meta-analysis

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Hepatobiliary & Pancreatic Diseases International 2021年第4期20卷 307-314页

作者： Paschalis Gavriilidis Keith j roberts Nicola de’Angelis Luca Aldrighetti robert P Sutcliffe Department of Hepato-Pancreato-Biliary and Liver Transplant Surgery Queen Elizabeth University Hospitals Birmingham NHS Foundation TrustB152THUnited Kingdom Department of Digestive Surgery University Hospital Henri Mondor(AP-HP)94010 Créteil and University of Paris EstCréteilFrance Division of Hepatobiliary surgery San Raffaele HospitalVia Olgettina 60Milan 20132Italy

Background: Gold standard for colorectal liver metastases(CRLM) remains hepatic resection(HR). However, patients with severe comorbidities, unresectable or deep-situated resectable CRLM are candidates for ablation. The aim of the study was to compare recurrence rate and survival benefit of the microwave ablation(MWA), radiofrequency ablation(RFA) and HR by conducting the first network meta-analysis. Data sources: Systematic search of the literature was conducted in the electronic databases. Both updated traditional and network meta-analyses were conducted and the results were compared between them. Results: HR cohort demonstrated significantly less local recurrence rate and better 3-and 5-year diseasefree(DFS) and overall survival(OS) compared to MWA and RFA cohorts. HR cohort included significantly younger patients and with significantly lower preoperative carcinoembryonic antigen(CEA) by 10.28 ng/m L compared to RFA cohort. Subgroup analysis of local recurrence and OS of solitary and ≤3 cm CRLMs did not demonstrate any discrepancies when compared with the whole sample. Conclusions: For resectable CRLM the treatment of choice still remains HR. MWA and RFA can be used as a single or adjunct treatment in patients with unresectable CRLM and/or prohibitive comorbidities.

关键词： Microwave ablation Radiofrequency ablation Hepatic resection Liver resection

Terlipressin versus placebo in living donor liver transplantation

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Hepatobiliary & Pancreatic Diseases International 2022年第1期21卷 76-79页

作者： Paschalis Gavriilidis Ernest Hidalgo robert P Sutcliffe Keith j roberts Department of Hepato-Pancreato-Biliary and Liver Transplant surgery Queen Elizabeth University Hospitals Birmingham NHS Foundation TrustBirmingham B152THUK Department of Hepato-Pancreatico-Biliary Surgery and Transplantation Hospital Universitari Vall d’HebronBarcelona 08035Spain

To the Editor:Terlipressin is a long-acting synthetic analogue of vasopressin,demonstrating several potential benefits in the context of living donor liver transplantation(LDLT).During the recipient hepatec-tomy,terlipressin reduces the portal ***,it may mitigate the extent of bowel congestion following portal vein *** decreasing portal hyperperfusion and hypertension,it protects the graft from further injury and improves renal blood flow.

关键词： donor liver Terlipressin

Quo vadis carbocatalysis?

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journal of Energy Chemistry 2021年第10期30卷 219-227,I0007页

作者： robert Schlögl Max-Planck-Institut für Chemische Energiekonversion Stiftstr.34-3645470 Mülheim an der RuhrGermany Fritz-Haber Institut der Max-Planck-Gesellschaft Faradayweg 4-614195 BerlinGermany

Prologue The rich scientific heritage of Dangsheng Su contains as substantial fraction his contributions to the field of catalysis with nanostructured carbon *** from microstructural analysis it became quickly clear that the richness of morphological and hence surface electronic variations in this class of materials should be suitable for the development of a science base for heterogeneous catalysis.

关键词： materials. catalysis. catalysis

TIME-DEPENDENT MORPHOLOGY OF POLYETHYLENE-POLYPROPYLENE BLENDS

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Chinese journal of Polymer Science 2002年第6期20卷 497-508页

作者： robert A. Shanks Department of Applied Chemistry CRC for Polymers RMIT University Melbourne Victoria Australia

The effect of time-temperature treatment on morphology of polyethylene-polypropylene (PE-PP) blends wasstudied to establish a relationship between thermal history, morphology and mechanical properties. Polypropylene (PP)homopolymers were used to blend with various polyethylenes (PE), including high density polyethylene (HDPE), lowdensity polyethylene (LDPE), linear low density polyethylene (LLDPE), and very and ultra low density polyethylene(VLDPE and ULDPE). The majority of the blends were prepared at a ratio of PE:PP = 80:20, while blends of PP and LLDPEwere prepared at various compositions. Thermal treatment was carried out at temperatures between the crystallizationtemperatures of PP and PEs to allow PP to crystallize first from the blends. On cooling further, PE crystallized too. A verydiffuse PP spherulite morphology in the PE matrix was formed in some partially miscible blends when PP was less than 20%by mass. Droplet-matrix structures were developed in other blends with either PP or PE as dispersed domains in a continuousmatrix, depending on the composition ratio. The scanning electron microscopy (SEM) images displayed a fibrillar structureof PP spherulite in the LLDPE-PP (80:20) and large droplets of PP in the HDPE-PP (80:20) blend, providing larger surfacearea and better bonding in the LLDPE-PP (80:20) blends. This explains why the blends with diffuse spherulite morphologyshowed greater improvement in tensile properties than droplet-matrix morphology blends after time-temperature treatment.

关键词： Polypropylene and polyethylene blends Thermal history Spherulite Morphology Mechanical properties

Co-occurrence of carbohydrate malabsorption and primary epiploic appendagitis

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World journal of Gastroenterology 2015年第35期21卷 10242-10245页

作者： Wolfgang j Schnedl Peter Kalmar Harald Mangge robert Krause Sandra j Wallner-Liebmann Practice for General Internal Medicine Department of Radiology Medical University of Graz Clinical Institute for Medical and Chemical Laboratory Diagnosis MUG Coordinator BioTechMed GrazMedical University of Graz Department of Internal Medicine Medical University of Graz Institute of Pathophysiology Centre for Molecular MedicineMedical University of Graz

Unspecific abdominal complaints including bloating and irregular bowel movements may be caused by carbohydrate malabsorption syndromes, e.g., lactose and fructose malabsorption. These symptoms were investigated with hydrogen(H2) breath tests and correlated to carbohydrate malabsorption. During performing these H2-breath tests the patient presented with an acute, localized, non-migratory pain in the left lower abdominal quadrant. Primary epiploic appendagitis is a rare cause of abdominal acute or subacute complaints and diagnosis of primary epiploic appendagitis(PEA) is made when computed tomography reveals a characteristic lesion. We report on a patient with cooccurrence of lactose and fructose malabsorption, which was treated successfully with a diet free of culprit carbohydrates, with PEA recovering without medication or surgical treatment within few days. Since the abdominal unspecific symptoms had been present for months, they appeared not to be correlated to the acute localized abdominal pain, therefore we speculate on a random co-occurrence of combined carbohydrate malabsorption and PEA.

关键词： Carbohydrate malabsorption Fructose malabsorption

Mercury photoreduction and photooxidation in lakes：Effects of filtration and dissolved organic carbon concentration

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journal of Environmental Sciences 2018年第6期30卷 151-159页

作者： Nelson j.O’Driscoll Emma Vost Erin Mann Sara Klapstein robert Tordon Matthew Lukeman Department of Earth & Environmental Science Acadia University Wolfville B4P 2R6 Nova Scotia Canada Environment Canada Dartmouth Nova Scotia Canada Department of Chemistry Acadia University Wolfville B4P 2R6 Nova Scotia Canada

Mercury is a globally distributed, environmental contaminant. Quantifying the retention and loss of mercury is integral for predicting mercury-sensitive ecosystems. There is little information on how dissolved organic carbon（DOC） concentrations and particulates affect mercury photoreaction kinetics in freshwater lakes. To address this knowledge gap,samples were collected from ten lakes in Kejimkujik National Park, Nova Scotia（DOC： 2.6–15.4 mg/L）. Filtered（0.2 μm） and unfiltered samples were analysed for gross photoreduction, gross photooxidation, and net reduction rates of mercury using pseudo first-order curves. Unfiltered samples had higher concentrations（p = 0.04） of photoreducible divalent mercury（Hg（II）RED）（mean of 754 ± 253 pg/L） than filtered samples（mean of 482 ± 206 pg/L）;however, gross photoreduction and photooxidation rate constants were not significantly different in filtered or unfiltered samples in early summer. DOC was not significantly related to gross photoreduction rate constants in filtered（R2= 0.43; p = 0.08） and unfiltered（R2= 0.02; p = 0.71） samples; DOC was also not significantly related to gross photooxidation rate constants in filtered or unfiltered samples. However, DOC was significantly negatively related with Hg（Ⅱ）RED in unfiltered（R2= 0.53; p = 0.04）, but not in filtered samples（R2= 0.04;p = 0.60）. These trends indicate that DOC is a factor in determining dissolved mercury photoreduction rates and particles partially control available Hg（Ⅱ）RED in lake water. This research also demonstrates that within these lakes gross photoreduction and photooxidation processes are close to being in balance. Changes to catchment inputs of particulate matter and DOC may alter mercury retention in these lakes and could partially explain observed increases of mercury accumulation in biota.

关键词： Mercury Photoreduction Photooxidation Dissolved organic carbon(DOC) Particulates Kejimkujik National Park

Tibet,the Himalaya,Asian monsoons and biodiversity-In what ways are they related？

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Plant Diversity 2017年第5期39卷 233-244页

作者： robert A. Spicer Key Laboratory of Tropical Forest Ecology Xishuangbanna Tropical Botanical Garden Chinese Academy of Sciences Menglun Yunnan 666303 PR China School of Environment Earth and Ecosystem Sciences The Open University MK7 6AA UK

Prevailing dogma asserts that the uplift of Tibet, the onset of the Asian monsoon system and high biodiversity in southern Asia are linked, and that all occurred after 23 million years ago in the ***, spanning the last 60 million years of Earth history, the geological, climatological and palaeontological evidence for this linkage is reviewed. The principal conclusions are that: 1) A proto-Tibetan highland existed well before the Neogene and that an Andean type topography with surface elevations of at least 4.5 km existed at the start of the Eocene, before final closure of the Tethys Ocean that separated India from Eurasia. 2) The Himalaya were formed not at the start of the India-Eurasia collision, but after much of Tibet had achieved its present elevation. The Himalaya built against a pre-existing proto-Tibetan highland and only projected above the average height of the plateau after approximately 15 Ma. 3)Monsoon climates have existed across southern Asia for the whole of the Cenozoic, and probably for a lot longer, but that they were of the kind generated by seasonal migrations of the Inter-tropical Convergence Zone. 4) The projection of the High Himalaya above the Tibetan Plateau at about 15 Ma coincides with the development of the modern South Asia Monsoon. 5) The East Asia monsoon became established in its present form about the same time as a consequence of topographic changes in northern Tibet and elsewhere in Asia, the loss of moisture sources in the Asian interior and the development of a strong winter Siberian high as global temperatures declined. 6) New radiometric dates of palaeontological finds point to southern Asia's high biodiversity originating in the Paleogene, not the Neogene.

关键词： Tibetan Plateau Himalaya Uplift history Monsoons Biodiversity Molecular phylogeny