SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "AMNE:(NATURAL SCIENCES Physical Sciences) ;spr:eng"

Sökning: AMNE:(NATURAL SCIENCES Physical Sciences) > Engelska

  • Resultat 1-10 av 85046
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  •  
2.
  • Le Breton, Michael, 1986, et al. (författare)
  • Chlorine oxidation of VOCs at a semi-rural site in Beijing: significant chlorine liberation from ClNO2 and subsequent gas- and particle-phase Cl-VOC production
  • 2018
  • Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 18:17, s. 13013-13030:18, s. 13013-13030
  • Tidskriftsartikel (refereegranskat)abstract
    • Nitryl chloride (ClNO2) accumulation at night acts as a significant reservoir for active chlorine and impacts the following day's photochemistry when the chlorine atom is liberated at sunrise. Here, we report simultaneous measurements of N2O5 and a suite of inorganic halogens including ClNO2 and reactions of chloride with volatile organic compounds (Cl-VOCs) in the gas and particle phases utilising the Filter Inlet for Gas and AEROsols time-of-flight chemical ionisation mass spectrometer (FIGAERO-ToF-CIMS) during an intensive measurement campaign 40 km northwest of Beijing in May and June 2016. A maximum mixing ratio of 2900 ppt of ClNO2 was observed with a mean campaign nighttime mixing ratio of 487 ppt, appearing to have an anthropogenic source supported by correlation with SO2, CO and benzene, which often persisted at high levels after sunrise until midday. This was attributed to such high mixing ratios persisting after numerous e-folding times of the photolytic lifetime enabling the chlorine atom production to reach 2.3 x 10(5) molecules cm(-3) from ClNO2 alone, peaking at 09:30 LT and up to 8.4 x 10(5) molecules cm(-3) when including the supporting inorganic halogen measurements. Cl-VOCs were observed in the particle and gas phases for the first time at high time resolution and illustrate how the iodide ToF-CIMS can detect unique markers of chlorine atom chemistry in ambient air from both biogenic and anthropogenic sources. Their presence and abundance can be explained via time series of their measured and steady-state calculated precursors, enabling the assessment of competing OH and chlorine atom oxidation via measurements of products from both of these mechanisms and their relative contribution to secondary organic aerosol (SOA) formation.
  •  
3.
  • Mohr, Claudia, et al. (författare)
  • Molecular identification of organic vapors driving atmospheric nanoparticle growth
  • 2019
  • Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 10
  • Tidskriftsartikel (refereegranskat)abstract
    • Particles formed in the atmosphere via nucleation provide about half the number of atmospheric cloud condensation nuclei, but in many locations, this process is limited by the growth of the newly formed particles. That growth is often via condensation of organic vapors. Identification of these vapors and their sources is thus fundamental for simulating changes to aerosol-cloud interactions, which are one of the most uncertain aspects of anthropogenic climate forcing. Here we present direct molecular-level observations of a distribution of organic vapors in a forested environment that can explain simultaneously observed atmospheric nanoparticle growth from 3 to 50 nm. Furthermore, the volatility distribution of these vapors is sufficient to explain nanoparticle growth without invoking particle-phase processes. The agreement between observed mass growth, and the growth predicted from the observed mass of condensing vapors in a forested environment thus represents an important step forward in the characterization of atmospheric particle growth.
  •  
4.
  • Guo, Y. D., et al. (författare)
  • Identification of highly oxygenated organic molecules and their role in aerosol formation in the reaction of limonene with nitrate radical
  • 2022
  • Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 22:17, s. 11323-11346
  • Tidskriftsartikel (refereegranskat)abstract
    • Nighttime NO3-initiated oxidation of biogenic volatile organic compounds (BVOCs) such as monoterpenes is important for the atmospheric formation and growth of secondary organic aerosol (SOA), which has significant impact on climate, air quality, and human health. In such SOA formation and growth, highly oxygenated organic molecules (HOM) may be crucial, but their formation pathways and role in aerosol formation have yet to be clarified. Among monoterpenes, limonene is of particular interest for its high emission globally and high SOA yield. In this work, HOM formation in the reaction of limonene with nitrate radical (NO3) was investigated in the SAPHIR chamber (Simulation of Atmospheric PHotochemistry In a large Reaction chamber). About 280 HOM products were identified, grouped into 19 monomer families, 11 dimer families, and 3 trimer families. Both closed-shell products and open-shell peroxy radicals (RO2 center dot) 2 were observed, and many of them have not been reported previously. Monomers and dimers accounted for 47% and 47% of HOM concentrations, respectively, with trimers making up the remaining 6 %. In the most abundant monomer families, C10H15-17NO6-14, carbonyl products outnumbered hydroxyl products, indicating the importance of RO2 center dot termination by unimolecular dissociation. Both RO2 center dot autoxidation and alkoxy-peroxy pathways were found to be important processes leading to HOM. Time-dependent concentration profiles of monomer products containing nitrogen showed mainly second-generation formation patterns. Dimers were likely formed via the accretion reaction of two monomer RO2 center dot , and HOM-trimers via the accretion reaction between monomer RO2 center dot and dimer RO2 center dot. Trimers are suggested to play an important role in new particle formation (NPF) observed in our experiment. A HOM yield of 1.5%(+1.7%)(-0.7%) was estimated considering only first-generation products. SOA mass growth could be reasonably explained by HOM condensation on particles assuming irreversible uptake of ultra-low volatility organic compounds (ULVOCs), extremely low volatility organic compounds (ELVOCs), and low volatility organic compounds (LVOCs). This work provides evidence for the important role of HOM formed via the limonene +NO3 reaction in NPF and growth of SOA particles.
  •  
5.
  • Farewell, Anne, 1961 (författare)
  • Rising to the Top: Promoting Deeper Learning in the Laboratory
  • 2018
  • Ingår i: National Center for Case Study Teaching in Science.
  • Bokkapitel (refereegranskat)abstract
    • Inquiry-based labs differ from cookbook labs in that inquiry-based labs contain an element of experimentation. A cookbook lab can be performed by a student without understanding any of the theory connected with the exercise whereas inquiry-based labs require a degree of conceptual knowledge for a student to perform the lab. Inquiry-based labs also strengthen and deepen students understanding of topics discussed in lectures or reading assignments. There are many variations and degrees of inquiry in these labs ranging from a lab that is entirely designed by the students to those that include small questions requiring that the students predict the outcomes of a lab or fill in missing information (guided inquiry). A simple specific example of a cookbook lab would be instructing students to measure volume changes between ice and liquid water. The students would be given step by step instructions to follow and would not need to apply any conceptual knowledge. An inquiry based lab on the same topic would allow the students to design their own experiment to discover how the volume of liquid water differs from that of ice. One goal of this activity is to introduce inquiry-based lab design. Beyond lab design, lab supervision is crucial to encouraging students to use their conceptual knowledge when doing a practical lab. Lab assistants or teachers who are involved in the lab can use student questions to encourage deeper understanding. This case study includes a role-play exercise for this skill. This case study has been designed to be used in science education courses for both graduate student laboratory assistants and lecturers or professors in natural sciences at the university or college level. It includes discussion and role-play of a hypothetical laboratory. No specific knowledge of biology or chemistry is needed beyond high school level to complete this task, though knowledge of the existence of microorganisms (yeast) and proteins is assumed. In addition, this activity is suitable for participants with little or no pedagogics training.
  •  
6.
  •  
7.
  • Wang, Y. J., et al. (författare)
  • The formation of nitro-aromatic compounds under high NOx and anthropogenic VOC conditions in urban Beijing, China
  • 2019
  • Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 19:11, s. 7649-7665
  • Tidskriftsartikel (refereegranskat)abstract
    • Nitro-aromatic compounds (NACs), as important contributors to the light absorption by brown carbon, have been widely observed in various ambient atmospheres; however, their formation in the urban atmosphere was little studied. In this work, we report an intensive field study of NACs in summer 2016 at an urban Beijing site, characterized by both high-NO(x)and anthropogenic VOC dominated conditions. We investigated the factors that influence NAC formation (e.g., NO2, VOC precursors, RH and photolysis) through quantification of eight NACs, along with major components in fine particulate matter, selected volatile organic compounds, and gases. The average total concentration of the quantified NACs was 6.63 ng m(-3), higher than those reported in other summertime studies (0.14-6.44 ng m(-3)). 4-Nitrophenol (4NP, 32.4 %) and 4-nitrocatechol (4NC, 28.5 %) were the top two most abundant NACs, followed by methyl-nitrocatechol (MNC), methyl-nitrophenol (MNP), and dimethyl-nitrophenol (DMNP). The oxidation of toluene and benzene in the presence of NOx was found to be a more dominant source of NACs than primary biomass burning emissions. The NO2 concentration level was found to be an important factor influencing the secondary formation of NACs. A transition from low- to high-NOx regimes coincided with a shift from organic- to inorganic-dominated oxidation products. The transition thresholds were NO2 similar to 20 ppb for daytime and NO2 similar to 25 ppb for nighttime conditions. Under low-NOx conditions, NACs increased with NO2, while the NO3 concentrations and (NO3-)/NACs ratios were lower, implying organic-dominated products. Under high-NOx conditions, NAC concentrations did not further increase with NO2, while the NO3- concentrations and (NO3-)/NACs ratios showed increasing trends, signaling a shift from organic- to inorganic-dominated products. Nighttime enhancements were observed for 3M4NC and 4M5NC, while daytime enhancements were noted for 4NP, 2M4NP, and DMNP, indicating different formation pathways for these two groups of NACs. Our analysis suggested that the aqueous-phase oxidation was likely the major formation pathway of 4M5NC and 3M5NC, while photo-oxidation of toluene and benzene in the presence of NO2 could be more important for the formation of nitrophenol and its derivatives. Using the (3M4NC+4M5NC) / 4NP ratios as an indicator of the relative contribution of aqueous-phase and gas-phase oxidation pathways to NAC formation, we observed that the relative contribution of aqueous-phase pathways increased at elevated ambient RH and remained constant at RH > 30 %. We also found that the concentrations of VOC precursors (e.g., toluene and benzene) and aerosol surface area acted as important factors in promoting NAC formation, and photolysis as an important loss pathway for nitrophenols.
  •  
8.
  • Dodig Crnkovic, Gordana, 1955 (författare)
  • Natural Computational Architectures for Cognitive Info-Communication
  • 2021
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Recent comprehensive overview of 40 years of research in cognitive architectures, (Kotseruba and Tsotsos 2020), evaluates modelling of the core cognitive abilities in humans, but only marginally addresses biologically plausible approaches based on natural computation. This mini review presents a set of perspectives and approaches which have shaped the development of biologically inspired computational models in the recent past that can lead to the development of biologically more realistic cognitive architectures. For describing continuum of natural cognitive architectures, from basal cellular to human-level cognition, we use evolutionary info-computational framework, where natural/ physical/ morphological computation leads to evolution of increasingly complex cognitive systems. Forty years ago, when the first cognitive architectures have been proposed, understanding of cognition, embodiment and evolution was different. So was the state of the art of information physics, bioinformatics, information chemistry, computational neuroscience, complexity theory, selforganization, theory of evolution, information and computation. Novel developments support a constructive interdisciplinary framework for cognitive architectures in the context of computing nature, where interactions between constituents at different levels of organization lead to complexification of agency and increased cognitive capacities. We identify several important research questions for further investigation that can increase understanding of cognition in nature and inspire new developments of cognitive technologies. Recently, basal cell cognition attracted a lot of interest for its possible applications in medicine, new computing technologies, as well as micro- and nanorobotics. Bio-cognition of cells connected into tissues/organs, and organisms with the group (social) levels of information processing provides insights into cognition mechanisms that can support the development of new AI platforms and cognitive robotics.
  •  
9.
  •  
10.
  • Vitalis Pemunta, Ngambouk, 1973, et al. (författare)
  • Modern State Law: Regulating Tradition or Protecting the Environment in the Mankon Kingdom of Northwest Cameroon?
  • 2019
  • Ingår i: Endemic Species. Eusebio Cano Carmona (red.). - London, United Kingdom : Intechopen. - 9781839623547 ; , s. 181-
  • Bokkapitel (refereegranskat)abstract
    • Most African countries including Cameroon find themselves in a situation of legal pluralism and at crossroads with implications for the sustainable management of natural resources. Traditional institutions and knowledge systems have been hailed as invaluable mechanisms for the conservation of flora and fauna. This chapter examines the conflict between traditional institutions and State law in the hierarchically stratified Mankon Kingdom of the Grassfield region of Northwest Cameroon where the latter prohibits the harvesting of culturally valuable plant and animal species for myriad ritual ceremonies and for therapeutic purposes. It demonstrates that the lack of cultural sensitivity can be antithetical to conservation initiatives. In other words, there is the need to align current legislative regulations for the management of natural species with the traditional use of territory, gender roles as well as to raise the cultural and educational level of the population through sensitization on the need to conserve the natural environment on which their culture depends for its survival.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-10 av 85046
Typ av publikation
tidskriftsartikel (63123)
konferensbidrag (11290)
doktorsavhandling (4693)
annan publikation (1437)
licentiatavhandling (1371)
forskningsöversikt (1148)
visa fler...
bokkapitel (946)
rapport (667)
bok (124)
patent (76)
samlingsverk (redaktörskap) (65)
proceedings (redaktörskap) (59)
konstnärligt arbete (37)
recension (27)
visa färre...
Typ av innehåll
refereegranskat (72839)
övrigt vetenskapligt/konstnärligt (11864)
populärvet., debatt m.m. (322)
Författare/redaktör
Strandberg, Jonas (1190)
Zwalinski, L. (1137)
Ekelöf, Tord (1116)
Ellert, Mattias (1064)
Brenner, Richard (1063)
Bohm, Christian (985)
visa fler...
Aad, G (874)
Abbott, B. (831)
Lund-Jensen, Bengt (805)
Silverstein, Samuel ... (801)
Moa, Torbjörn (754)
Hellman, Sten (732)
Zhu, J. (720)
Meyer, J. (703)
Doglioni, Caterina (689)
Oskarsson, Anders (665)
Peters, K. (654)
Smirnova, Oxana (638)
Liu, Y. (634)
Stenlund, Evert (623)
Hedberg, Vincent (607)
Mjörnmark, Ulf (601)
Lokajicek, M. (600)
Jarlskog, Göran (599)
Quadt, A. (598)
Evans, H. (596)
Qian, J. (596)
Fox, H. (595)
Burdin, S. (594)
Zhou, B. (593)
Brock, R. (592)
Gutierrez, P. (592)
Kehoe, R. (592)
Snyder, S. (592)
Kupco, A. (591)
Pleier, M. -A. (591)
Sawyer, L. (591)
Schwienhorst, R. (591)
Borissov, G. (590)
Brandt, A. (590)
Stark, J. (590)
Cooke, M. (589)
Fiedler, F. (589)
Khanov, A. (589)
Rizatdinova, F. (589)
Severini, H. (589)
Shabalina, E. (589)
Strauss, M. (589)
Tsybychev, D. (589)
Watts, G. (589)
visa färre...
Lärosäte
Lunds universitet (19420)
Kungliga Tekniska Högskolan (17543)
Uppsala universitet (17173)
Chalmers tekniska högskola (14960)
Stockholms universitet (10856)
Linköpings universitet (4002)
visa fler...
Göteborgs universitet (3673)
Umeå universitet (3203)
Luleå tekniska universitet (2190)
Linnéuniversitetet (1111)
Karlstads universitet (949)
RISE (757)
Malmö universitet (501)
Mittuniversitetet (461)
Örebro universitet (424)
Sveriges Lantbruksuniversitet (338)
Högskolan i Halmstad (297)
Karolinska Institutet (208)
Mälardalens universitet (160)
Högskolan i Gävle (156)
Jönköping University (99)
Högskolan Dalarna (88)
Högskolan Kristianstad (84)
Högskolan i Borås (78)
Högskolan i Skövde (65)
Södertörns högskola (37)
Blekinge Tekniska Högskola (34)
Högskolan Väst (31)
Naturhistoriska riksmuseet (15)
IVL Svenska Miljöinstitutet (11)
Försvarshögskolan (7)
Handelshögskolan i Stockholm (5)
VTI - Statens väg- och transportforskningsinstitut (4)
Gymnastik- och idrottshögskolan (2)
Konstfack (1)
Röda Korsets Högskola (1)
visa färre...
Språk
Forskningsämne (UKÄ/SCB)
Naturvetenskap (85007)
Teknik (8544)
Medicin och hälsovetenskap (1014)
Samhällsvetenskap (633)
Lantbruksvetenskap (294)
Humaniora (176)

År

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy