TY - JOUR A1 - Liu, Shuyan A1 - Schad, Daniel A1 - Kuschpel, Maxim S. A1 - Rapp, Michael A. A1 - Heinz, Andreas T1 - Music and Video Gaming during Breaks BT - Influence on Habitual versus Goal-Directed Decision Making JF - PLoS one N2 - Different systems for habitual versus goal-directed control are thought to underlie human decision-making. Working memory is known to shape these decision-making systems and their interplay, and is known to support goal-directed decision making even under stress. Here, we investigated if and how decision systems are differentially influenced by breaks filled with diverse everyday life activities known to modulate working memory performance. We used a within-subject design where young adults listened to music and played a video game during breaks interleaved with trials of a sequential two-step Markov decision task, designed to assess habitual as well as goal-directed decision making. Based on a neurocomputational model of task performance, we observed that for individuals with a rather limited working memory capacity video gaming as compared to music reduced reliance on the goal-directed decision-making system, while a rather large working memory capacity prevented such a decline. Our findings suggest differential effects of everyday activities on key decision-making processes. KW - Decision making KW - Games KW - Working memory KW - Video games KW - Cognition KW - Cognitive impairment KW - Music cognition KW - Learning Y1 - 2016 U6 - https://doi.org/10.1371/JOURNAL.PONE.0150165 SN - 1932-6203 VL - 11 IS - 3 SP - 1 EP - 12 PB - Public Library of Science CY - Lawrence, Kan. ER - TY - JOUR A1 - Wacker, Alexander A1 - Piepho, Maike A1 - Harwood, John L. A1 - Guschina, Irina A. A1 - Arts, Michael T. T1 - Light-Induced Changes in Fatty Acid Profiles of Specific Lipid Classes in Several Freshwater Phytoplankton Species JF - Frontiers in plant science : FPLS N2 - We tested the influence of two light intensities [40 and 300 μmol PAR / (m2s)] on the fatty acid composition of three distinct lipid classes in four freshwater phytoplankton species. We chose species of different taxonomic classes in order to detect potentially similar reaction characteristics that might also be present in natural phytoplankton communities. From samples of the bacillariophyte Asterionella formosa, the chrysophyte Chromulina sp., the cryptophyte Cryptomonas ovata and the zygnematophyte Cosmarium botrytis we first separated glycolipids (monogalactosyldiacylglycerol, digalactosyldiacylglycerol, and sulfoquinovosyldiacylglycerol), phospholipids (phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, and phosphatidylserine) as well as non-polar lipids (triacylglycerols), before analyzing the fatty acid composition of each lipid class. High variation in the fatty acid composition existed among different species. Individual fatty acid compositions differed in their reaction to changing light intensities in the four species. Although no generalizations could be made for species across taxonomic classes, individual species showed clear but small responses in their ecologically-relevant omega-3 and omega-6 polyunsaturated fatty acids (PUFA) in terms of proportions and of per tissue carbon quotas. Knowledge on how lipids like fatty acids change with environmental or culture conditions is of great interest in ecological food web studies, aquaculture, and biotechnology, since algal lipids are the most important sources of omega-3 long-chain PUFA for aquatic and terrestrial consumers, including humans. KW - freshwater algae KW - light adaptation KW - lipid classes KW - fatty acid changes Y1 - 2016 U6 - https://doi.org/10.3389/fpls.2016.00264 SN - 1664-462X VL - 7 SP - 1 EP - 13 PB - Frontiers Media CY - Lausanne ER - TY - JOUR A1 - Nicenboim, Bruno A1 - Logacev, Pavel A1 - Gattei, Carolina A1 - Vasishth, Shravan T1 - When High-Capacity Readers Slow Down and Low-Capacity Readers Speed Up BT - Working Memory and Locality Effects JF - Frontiers in psychology N2 - We examined the effects of argument-head distance in SVO and SOV languages (Spanish and German), while taking into account readers' working memory capacity and controlling for expectation (Levy, 2008) and other factors. We predicted only locality effects, that is, a slowdown produced by increased dependency distance (Gibson, 2000; Lewis and Vasishth, 2005). Furthermore, we expected stronger locality effects for readers with low working memory capacity. Contrary to our predictions, low-capacity readers showed faster reading with increased distance, while high-capacity readers showed locality effects. We suggest that while the locality effects are compatible with memory-based explanations, the speedup of low-capacity readers can be explained by an increased probability of retrieval failure. We present a computational model based on ACT-R built under the previous assumptions, which is able to give a qualitative account for the present data and can be tested in future research. Our results suggest that in some cases, interpreting longer RTs as indexing increased processing difficulty and shorter RTs as facilitation may be too simplistic: The same increase in processing difficulty may lead to slowdowns in high-capacity readers and speedups in low-capacity ones. Ignoring individual level capacity differences when investigating locality effects may lead to misleading conclusions. KW - locality KW - working memory capacity KW - individual differences KW - Spanish KW - German KW - ACT-R Y1 - 2016 U6 - https://doi.org/10.3389/fpsyg.2016.00280 SN - 1664-1078 VL - 7 SP - 1 EP - 24 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Rätzel, Dennis A1 - Wilkens, Martin A1 - Menzel, Ralf T1 - Gravitational properties of light BT - the gravitational field of a laser pulse JF - New journal of physics : the open-access journal for physics N2 - The gravitational field of a laser pulse of finite lifetime, is investigated in the framework of linearized gravity. Although the effects are very small, they may be of fundamental physical interest. It is shown that the gravitational field of a linearly polarized light pulse is modulated as the norm of the corresponding electric field strength, while no modulations arise for circular polarization. In general, the gravitational field is independent of the polarization direction. It is shown that all physical effects are confined to spherical shells expanding with the speed of light, and that these shells are imprints of the spacetime events representing emission and absorption of the pulse. Nearby test particles at rest are attracted towards the pulse trajectory by the gravitational field due to the emission of the pulse, and they are repelled from the pulse trajectory by the gravitational field due to its absorption. Examples are given for the size of the attractive effect. It is recovered that massless test particles do not experience any physical effect if they are co-propagating with the pulse, and that the acceleration of massless test particles counter-propagating with respect to the pulse is four times stronger than for massive particles at rest. The similarities between the gravitational effect of a laser pulse and Newtonian gravity in two dimensions are pointed out. The spacetime curvature close to the pulse is compared to that induced by gravitational waves from astronomical sources. KW - gravity KW - general relativity KW - laser pulses KW - electromagnetic radiation KW - linearized gravity KW - pp-wave solutions Y1 - 2016 U6 - https://doi.org/10.1088/1367-2630/18/2/023009 SN - 1367-2630 VL - 18 SP - 1 EP - 16 PB - IOP Science CY - London ER - TY - JOUR A1 - Höhle, Barbara A1 - Fritzsche, Tom A1 - Müller, Anja T1 - Children’s Comprehension of Sentences with Focus Particles and the Role of Cognitive Control BT - An Eye Tracking Study with German-Learning 4-Year-Olds JF - PLoS one N2 - Children’s interpretations of sentences containing focus particles do not seem adult-like until school age. This study investigates how German 4-year-old children comprehend sentences with the focus particle ‘nur’ (only) by using different tasks and controlling for the impact of general cognitive abilities on performance measures. Two sentence types with ‘only’ in either pre-subject or pre-object position were presented. Eye gaze data and verbal responses were collected via the visual world paradigm combined with a sentence-picture verification task. While the eye tracking data revealed an adult-like pattern of focus particle processing, the sentence-picture verification replicated previous findings of poor comprehension, especially for ‘only’ in pre-subject position. A second study focused on the impact of general cognitive abilities on the outcomes of the verification task. Working memory was related to children’s performance in both sentence types whereas inhibitory control was selectively related to the number of errors for sentences with ‘only’ in pre-subject position. These results suggest that children at the age of 4 years have the linguistic competence to correctly interpret sentences with focus particles, which–depending on specific task demands–may be masked by immature general cognitive abilities. KW - eyes KW - sentence processing KW - cognition KW - cognitive linguistics KW - human performance KW - syntax KW - cognitive psychology KW - working memory Y1 - 2016 U6 - https://doi.org/10.1371/journal.pone.0149870 SN - 1932-6203 VL - 11 IS - 3 SP - 1 EP - 27 PB - PLoS CY - Lawrence, Kan. ER - TY - JOUR A1 - Brand, Ralf A1 - Koch, Helen T1 - Using Caffeine Pills for Performance Enhancement BT - An Experimental Study on University Students’ Willingness and Their Intention to Try Neuroenhancements JF - Frontiers in psychology N2 - Recent research has indicated that university students sometimes use caffeine pills for neuroenhancement (NE; non-medical use of psychoactive substances or technology to produce a subjective enhancement in psychological functioning and experience), especially during exam preparation. In our factorial survey experiment, we manipulated the evidence participants were given about the prevalence of NE amongst peers and measured the resulting effects on the psychological predictors included in the Prototype-Willingness Model of risk behavior. Two hundred and thirty-one university students were randomized to a high prevalence condition (read faked research results overstating usage of caffeine pills amongst peers by a factor of 5; 50%), low prevalence condition (half the estimated prevalence; 5%) or control condition (no information about peer prevalence). Structural equation modeling confirmed that our participants’ willingness and intention to use caffeine pills in the next exam period could be explained by their past use of neuroenhancers, attitude to NE and subjective norm about use of caffeine pills whilst image of the typical user was a much less important factor. Provision of inaccurate information about prevalence reduced the predictive power of attitude with respect to willingness by 40-45%. This may be because receiving information about peer prevalence which does not fit with their perception of the social norm causes people to question their attitude. Prevalence information might exert a deterrent effect on NE via the attitude-willingness association. We argue that research into NE and deterrence of associated risk behaviors should be informed by psychological theory. KW - attitude KW - prevalence information KW - prototype-willingness-model KW - social reactivity KW - doping Y1 - 2016 U6 - https://doi.org/10.3389/fpsyg.2016.00101 SN - 1664-1078 VL - 7 SP - 1 EP - 11 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Paape, Dario L. J. F. T1 - Filling the Silence BT - Reactivation, not Reconstruction JF - Frontiers in psychology N2 - In a self-paced reading experiment, we investigated the processing of sluicing constructions (“sluices”) whose antecedent contained a known garden-path structure in German. Results showed decreased processing times for sluices with garden-path antecedents as well as a disadvantage for antecedents with non-canonical word order downstream from the ellipsis site. A post-hoc analysis showed the garden-path advantage also to be present in the region right before the ellipsis site. While no existing account of ellipsis processing explicitly predicted the results, we argue that they are best captured by combining a local antecedent mismatch effect with memory trace reactivation through reanalysis. KW - ellipsis processing KW - garden-path effect KW - German KW - retrieval KW - reconstruction KW - self-paced reading Y1 - 2016 U6 - https://doi.org/10.3389/fpsyg.2016.00027 SN - 1664-1078 VL - 7 SP - 1 EP - 18 PB - Frontiers Research Foundation CY - Lausanne ER - TY - THES A1 - Saleh, Eyad T1 - Securing Multi-tenant SaaS Environments N2 - Software-as-a-Service (SaaS) offers several advantages to both service providers and users. Service providers can benefit from the reduction of Total Cost of Ownership (TCO), better scalability, and better resource utilization. On the other hand, users can use the service anywhere and anytime, and minimize upfront investment by following the pay-as-you-go model. Despite the benefits of SaaS, users still have concerns about the security and privacy of their data. Due to the nature of SaaS and the Cloud in general, the data and the computation are beyond the users' control, and hence data security becomes a vital factor in this new paradigm. Furthermore, in multi-tenant SaaS applications, the tenants become more concerned about the confidentiality of their data since several tenants are co-located onto a shared infrastructure. To address those concerns, we start protecting the data from the provisioning process by controlling how tenants are being placed in the infrastructure. We present a resource allocation algorithm designed to minimize the risk of co-resident tenants called SecPlace. It enables the SaaS provider to control the resource (i.e., database instance) allocation process while taking into account the security of tenants as a requirement. Due to the design principles of the multi-tenancy model, tenants follow some degree of sharing on both application and infrastructure levels. Thus, strong security-isolation should be present. Therefore, we develop SignedQuery, a technique that prevents one tenant from accessing others' data. We use the Signing Concept to create a signature that is used to sign the tenant's request, then the server can verifies the signature and recognizes the requesting tenant, and hence ensures that the data to be accessed is belonging to the legitimate tenant. Finally, Data confidentiality remains a critical concern due to the fact that data in the Cloud is out of users' premises, and hence beyond their control. Cryptography is increasingly proposed as a potential approach to address such a challenge. Therefore, we present SecureDB, a system designed to run SQL-based applications over an encrypted database. SecureDB captures the schema design and analyzes it to understand the internal structure of the data (i.e., relationships between the tables and their attributes). Moreover, we determine the appropriate partialhomomorphic encryption scheme for each attribute where computation is possible even when the data is encrypted. To evaluate our work, we conduct extensive experiments with di↵erent settings. The main use case in our work is a popular open source HRM application, called OrangeHRM. The results show that our multi-layered approach is practical, provides enhanced security and isolation among tenants, and have a moderate complexity in terms of processing encrypted data. Y1 - 2016 ER - TY - JOUR A1 - Müller, Steffen A1 - Carlsohn, Anja A1 - Müller, Juliane A1 - Baur, Heiner A1 - Mayer, Frank T1 - Influence of Obesity on Foot Loading Characteristics in Gait for Children Aged 1 to 12 Years JF - PLoS one N2 - Background Overweight and obesity are increasing health problems that are not restricted to adults only. Childhood obesity is associated with metabolic, psychological and musculoskeletal comorbidities. However, knowledge about the effect of obesity on the foot function across maturation is lacking. Decreased foot function with disproportional loading characteristics is expected for obese children. The aim of this study was to examine foot loading characteristics during gait of normal-weight, overweight and obese children aged 1-12 years. Methods A total of 10382 children aged one to twelve years were enrolled in the study. Finally, 7575 children (m/f: n = 3630/3945; 7.0 +/- 2.9yr; 1.23 +/- 0.19m; 26.6 +/- 10.6kg; BMI: 17.1 +/- 2.4kg/m(2)) were included for (complete case) data analysis. Children were categorized to normalweight (>= 3rd and <90th percentile; n = 6458), overweight (>= 90rd and <97th percentile; n = 746) or obese (>97th percentile; n = 371) according to the German reference system that is based on age and gender-specific body mass indices (BMI). Plantar pressure measurements were assessed during gait on an instrumented walkway. Contact area, arch index (AI), peak pressure (PP) and force time integral (FTI) were calculated for the total, fore-, mid-and hindfoot. Data was analyzed descriptively (mean +/- SD) followed by ANOVA/Welch-test (according to homogeneity of variances: yes/no) for group differences according to BMI categorization (normal-weight, overweight, obesity) and for each age group 1 to 12yrs (post-hoc Tukey Kramer/Dunnett's C; alpha = 0.05). Results Mean walking velocity was 0.95 +/- 0.25 m/s with no differences between normal-weight, overweight or obese children (p = 0.0841). Results show higher foot contact area, arch index, peak pressure and force time integral in overweight and obese children (p< 0.001). Obese children showed the 1.48-fold (1 year-old) to 3.49-fold (10 year-old) midfoot loading (FTI) compared to normal-weight. Conclusion Additional body mass leads to higher overall load, with disproportional impact on the midfoot area and longitudinal foot arch showing characteristic foot loading patterns. Already the feet of one and two year old children are significantly affected. Childhood overweight and obesity is not compensated by the musculoskeletal system. To avoid excessive foot loading with potential risk of discomfort or pain in childhood, prevention strategies should be developed and validated for children with a high body mass index and functional changes in the midfoot area. The presented plantar pressure values could additionally serve as reference data to identify suspicious foot loading patterns in children. KW - plantar pressure distribution KW - body-mass index KW - prepubescent children KW - overweight children KW - childhood obesity KW - walking KW - speed KW - forces KW - adolescents KW - prevalence Y1 - 2016 U6 - https://doi.org/10.1371/journal.pone.0149924 SN - 1932-6203 VL - 11 IS - 2 PB - Public Library of Science CY - Lawrence, Kan. ER - TY - THES A1 - Quast, Robert B. T1 - Synthesis and site-directed modification of membrane proteins using non-canonical amino acids in a cell-free system derived from cultured Spodoptera frugiperda cells Y1 - 2015 ER - TY - THES A1 - Kondic, Todor T1 - Hall-MHD Instabilities of Shear Flows in Neutron Stars Y1 - 2015 ER - TY - THES A1 - Pratsch, Stephanie T1 - The Role of Aspirations in Negotiation T2 - Schriftenreihe zum Verhandlungsmanagement ; 4 N2 - Buyer-seller negotiations have significant impact on a company’s profitability, which makes practitioners aim at maximizing their performance. One lever for increasing bargaining performance is to pursue a clearly defined aspiration, i.e. one’s most desired outcome. In this context, the author explores the role of such aspirations in the three negotiation phases: preparation, bargaining, and striking a deal. She investigates determinants of aspirations, unintended consequences such as unethical bargaining behavior, and the consequences of overly ambitious aspirations. As a result, she does not only close existing gaps in negotiation research, but also derives valuable implications for practitioners Y1 - 2016 SN - 978-3-8300-9006-9 PB - Hamburg CY - Kovac ER - TY - THES A1 - Deffa, Oromiya-Jalata T1 - Discursive Construction of Bicultural Identity BT - a cross-generational sociolinguistic study on Oromo-Americans in Minnesota T2 - Duisburger Arbeiten zur Sprach- und Kulturwissenschaft ; 113 N2 - The author examines the cultural identity development of Oromo-Americans in Minnesota, an ethnic group originally located within the national borders of Ethiopia. Earlier studies on language and cultural identity have shown that the degree of ethnic orientation of minorities commonly decreases from generation to generation. Yet oppression and a visible minority status were identified as factors delaying the process of de-ethnicization. Given that Oromos fled persecution in Ethiopia and are confronted with the ramifications of a visible minority status in the U.S., it can be expected that they have retained strong ties to their ethnic culture. This study, however, came to a more complex and theory-building result. Y1 - 2016 SN - 978-3-631-67312-6 PB - Lang CY - Frankfurt am Main ER - TY - JOUR A1 - Prinz, Julia A1 - Heck, Christian A1 - Ellerik, Lisa A1 - Merk, Virginia A1 - Bald, Ilko T1 - DNA origami based Au–Ag-core–shell nanoparticle dimers with single-molecule SERS sensitivity JF - Nanoscale N2 - DNA origami nanostructures are a versatile tool to arrange metal nanostructures and other chemical entities with nanometer precision. In this way gold nanoparticle dimers with defined distance can be constructed, which can be exploited as novel substrates for surface enhanced Raman scattering (SERS). We have optimized the size, composition and arrangement of Au/Ag nanoparticles to create intense SERS hot spots, with Raman enhancement up to 1010, which is sufficient to detect single molecules by Raman scattering. This is demonstrated using single dye molecules (TAMRA and Cy3) placed into the center of the nanoparticle dimers. In conjunction with the DNA origami nanostructures novel SERS substrates are created, which can in the future be applied to the SERS analysis of more complex biomolecular targets, whose position and conformation within the SERS hot spot can be precisely controlled. Y1 - 2016 U6 - https://doi.org/10.1039/C5NR08674D IS - 8 SP - 5612 EP - 5620 PB - RSC Publishing CY - Cambridge ER - TY - JOUR A1 - Mondal, Suvendu Sekhar A1 - Marquardt, Dorothea A1 - Janiak, Christoph A1 - Holdt, Hans-Jürgen T1 - Use of a 4,5-dicyanoimidazolate anion based ionic liquid for the synthesis of iron and silver nanoparticles JF - Dalton transactions : an international journal of inorganic chemistry N2 - Sixteen new ionic liquids (ILs) with tetraethylammonium, 1-butyl-3-methylimidazolium, 3-methyl-1-octylimidazolium and tetrabutylphosphonium cations paired with 2-substituted 4,5-dicyanoimidazolate anions (substituent at C2 = methyl, trifluoromethyl, pentafluoroethyl, N,N′-dimethyl amino and nitro) have been synthesized and characterized by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA). The effects of cation and anion type and structure of the resulting ILs, including several room temperature ionic liquids (RTILs), are reflected in the crystallization, melting points and thermal decomposition of the ILs. ILs exhibited large liquid and crystallization ranges and formed glasses on cooling with glass transition temperatures in the range of −22 to −71 °C. We selected one of the newly designed ILs due to its bigger size, compared to the common conventional IL anion and high electron-withdrawing nitrile group leads to an overall stabilization anion that may stabilize the metal nanoparticles. Stable and better separated iron and silver nanoparticles are obtained by the decomposition of corresponding Fe2(CO)9 and AgPF6, respectively, under N2-atmosphere in newly designed nitrile functionalized 4,5-dicyanoimidazolate anion based IL. Very small and uniform size for Fe-nanoparticles of about 1.8 ± 0.6 nm were achieved without any additional stabilizers or capping molecules. Comparatively bigger size of Ag-nanoparticles was obtained through the reduction of AgPF6 by hydrogen gas. Additionally, the AgPF6 precursor was decomposed under microwave irradiation (MWI), fabricating nut-in-shell-like, that is, core-separated-from-shell Ag-nano-structures. Y1 - 2016 U6 - https://doi.org/10.1039/C6DT00225K SN - 1477-9226 IS - 45 SP - 5476 EP - 5483 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Klaper, M. A1 - Wessig, Pablo A1 - Linker, Torsten T1 - Base catalysed decomposition of anthracene endoperoxide JF - Chemical communications : ChemComm N2 - Catalytic amounts of a weak base are sufficient to induce the decomposition of anthracene endoperoxides to anthraquinone. The mechanism has been elucidated by isolation of intermediates in combination with DFT calculations. The whole process is suitable for the convenient generation of hydrogen peroxide under very mild conditions. Y1 - 2015 U6 - https://doi.org/10.1039/C5CC08606J SN - 1364-548X IS - 52 SP - 1210 EP - 1213 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Matis, Jochen René A1 - Schönborn, Jan Boyke A1 - Saalfrank, Peter T1 - A multi-reference study of the byproduct formation for a ring-closed dithienylethene photoswitch JF - Physical chemistry, chemical physics : PCCP ; a journal of European Chemical Societies N2 - Photodriven molecular switches are sometimes hindered in their performance by forming byproducts which act as dead ends in sequences of switching cycles, leading to rapid fatigue effects. Understanding the reaction pathways to unwanted byproducts is a prerequisite for preventing them. This article presents a study of the photochemical reaction pathways for byproduct formation in the photochromic switch 1,2-bis-(3-thienyl)-ethene. Specifically, using single- and multi-reference methods the post-deexcitation reaction towards the byproduct in the electronic ground state S0 when starting from the S1–S0 conical intersection (CoIn), is considered in detail. We find an unusual low-energy pathway, which offers the possibility for the formation of a dyotropic byproduct. Several high-energy pathways can be excluded with high probability. Y1 - 2015 U6 - https://doi.org/10.1039/C5CP00987A SN - 1463-9076 SN - 1463-9084 IS - 17 SP - 14088 EP - 14095 PB - The Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Prestel, Andreas A1 - Möller, Heiko Michael T1 - Spatio-temporal control of cellular uptake achieved by photoswitchable cell-penetrating peptides JF - Chemical communications : ChemComm N2 - The selective uptake of compounds into specific cells of interest is a major objective in cell biology and drug delivery. By incorporation of a novel, thermostable azobenzene moiety we generated peptides that can be switched optically between an inactive state and an active, cell-penetrating state with excellent spatio-temporal control. Y1 - 2015 U6 - https://doi.org/10.1039/C5CC06848G SN - 1364-548X IS - 52 SP - 701 EP - 704 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Klier, Dennis Tobias A1 - Kumke, Michael Uwe T1 - Analysing the effect of the crystal structure on upconversion luminescence in Yb3+,Er3+-co-doped NaYF4 nanomaterials JF - Journal of materials chemistry C ; Materials for optical and electronic devices N2 - NaYF4:Yb:Er nanoparticles (UCNP) were synthesized under mild experimental conditions to obtain a pure cubic lattice. Upon annealing at different temperatures up to Tan = 700 °C phase transitions to the hexagonal phase and back to the cubic phase were induced. The UCNP materials obtained for different Tan were characterized with respect to the lattice phase using standard XRD and Raman spectroscopy as well as steady state and time resolved upconversion luminescence. The standard techniques showed that for the annealing temperature range 300 °C < Tan < 600 °C the hexagonal lattice phase was dominant. For Tan < 300 °C hardly any change in the lattice phase could be deduced, whereas for Tan > 600 °C a back transfer to the α-phase was observed. Complementarily, the luminescence upconversion properties of the annealed UCNP materials were characterized in steady state and time resolved luminescence measurements. Distinct differences in the upconversion luminescence intensity, the spectral intensity distribution and the luminescence decay kinetics were found for the cubic and hexagonal lattice phases, respectively, corroborating the results of the standard analytical techniques used. In laser power dependent measurements of the upconversion luminescence intensity it was found that the green (G1, G2) and red (R) emission of Er3+ showed different effects of Tan on the number of required photons reflecting the differences in the population routes of different energy levels involved. Furthermore, the intensity ratio of Gfull/R is highly effected by the laser power only when the β-phase is present, whereas the G1/G2 intensity ratio is only slightly effected regardless of the crystal phase. Moreover, based on different upconversion luminescence kinetics characteristics of the cubic and hexagonal phase time-resolved area normalized emission spectra (TRANES) proved to be a very sensitive tool to monitor the phase transition between cubic and hexagonal phases. Based on the TRANES analysis it was possible to resolve the lattice phase transition in more detail for 200 °C < Tan < 300 °C, which was not possible with the standard techniques. Y1 - 2015 U6 - https://doi.org/10.1039/C5TC02218E SN - 2050-7526 SN - 2050-7534 IS - 3 SP - 11228 EP - 11238 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Klier, Dennis Tobias A1 - Kumke, Michael Uwe T1 - Upconversion NaYF4:Yb:Er nanoparticles co-doped with Gd3+ and Nd3+ for thermometry on the nanoscale JF - RSC Advances : an international journal to further the chemical sciences N2 - In the present work, the upconversion luminescence properties of oleic acid capped NaYF4:Gd3+:Yb3+:Er3+ upconversion nanoparticles (UCNP) with pure β crystal phase and Nd3+ ions as an additional sensitizer were studied in the temperature range of 288 K < T < 328 K. The results of this study showed that the complex interplay of different mechanisms and effects, causing the special temperature behavior of the UCNP can be developed into thermometry on the nanoscale, e.g. to be applied in biological systems on a cellular level. The performance was improved by the use of Nd3+ as an additional dopant utilizing the cascade sensitization mechanism in tri-doped UCNP. Y1 - 2015 U6 - https://doi.org/10.1039/C5RA11502G SN - 2046-2069 IS - 5 SP - 67149 EP - 67156 PB - RSC Publishing CY - London ER -