Showing papers by "Bielefeld University published in 2012"

Three-Dimensional Nitrogen and Boron Co-doped Graphene for High-Performance All-Solid-State Supercapacitors

Abstract: carbide-derived carbon, [ 12 ] carbon nanotubes (CNTs), [ 14–17 ] and graphene, [ 6 , 7 , 10 , 18 , 19 ] possess notable features including high surface area, high electrical conductivity, and good chemical stability, and therefore they have been widely explored as thinfi lm electrode materials for ASSSs. However, the fabrication of ASSSs generally involves complex solution processing, highpressure pressing, high-temperature sintering, and sputtering techniques. [ 11 , 12 , 14–17 ] Moreover, polymer binders and conductive additives are required to enhance the adhesion between electrode materials and substrates as well as to improve the conductivity of the electrode, which unavoidably leads to decreased energy density of the devices. [ 6 , 20 ] Therefore, several challenges remain in developing ASSSs, such as to: i) explore high-performance electrode materials, ii) enhance the interfacial compatibility between electrode and solid-state electrolyte, and iii) simplify the device fabrication process. Graphene aerogels (GAs) represent a new class of ultralight and porous carbon materials that are associated with high

Chiral and deconfinement aspects of the QCD transition

Abstract: We present results on the chiral and deconfinement properties of the QCD transition at finite temperature. Calculations are performed with $2+1$ flavors of quarks using the p4, asqtad, and HISQ/tree actions. Lattices with temporal extent ${N}_{\ensuremath{\tau}}=6$, 8, and 12 are used to understand and control discretization errors and to reliably extrapolate estimates obtained at finite lattice spacings to the continuum limit. The chiral transition temperature is defined in terms of the phase transition in a theory with two massless flavors and analyzed using $O(N)$ scaling fits to the chiral condensate and susceptibility. We find consistent estimates from the HISQ/tree and asqtad actions and our main result is ${T}_{c}=154\ifmmode\pm\else\textpm\fi{}9\text{ }\text{ }\mathrm{MeV}$.

Template-based question answering over RDF data

Abstract: As an increasing amount of RDF data is published as Linked Data, intuitive ways of accessing this data become more and more important. Question answering approaches have been proposed as a good compromise between intuitiveness and expressivity. Most question answering systems translate questions into triples which are matched against the RDF data to retrieve an answer, typically relying on some similarity metric. However, in many cases, triples do not represent a faithful representation of the semantic structure of the natural language question, with the result that more expressive queries can not be answered. To circumvent this problem, we present a novel approach that relies on a parse of the question to produce a SPARQL template that directly mirrors the internal structure of the question. This template is then instantiated using statistical entity identification and predicate detection. We show that this approach is competitive and discuss cases of questions that can be answered with our approach but not with competing approaches.

Agent-based simulation of innovation diffusion: A review

Abstract: Mathematical modeling of innovation diffusion has attracted strong academic interest since the early 1960s. Traditional diffusion models have aimed at empirical generalizations and hence describe the spread of new products parsimoniously at the market level. More recently, agent-based modeling and simulation has increasingly been adopted since it operates on the individual level and, thus, can capture complex emergent phenomena highly relevant in diffusion research. Agent-based methods have been applied in this context both as intuition aids that facilitate theory-building and as tools to analyze real-world scenarios, support management decisions and obtain policy recommendations. This review addresses both streams of research. We critically examine the strengths and limitations of agent-based modeling in the context of innovation diffusion, discuss new insights agent-based models have provided, and outline promising opportunities for future research. The target audience of the paper includes both researchers in marketing interested in new findings from the agent-based modeling literature and researchers who intend to implement agent-based models for their own research endeavors. Accordingly, we also cover pivotal modeling aspects in depth (concerning, e.g., consumer adoption behavior and social influence) and outline existing models in sufficient detail to provide a proper entry point for researchers new to the field.

From serendipity to design of polyoxometalates at the nanoscale, aesthetic beauty and applications

Abstract: Polyoxometalate cluster science has come a long way since the first description of molybdenum blue in 1778 by the famous Swedish chemist Scheele. Interestingly, it was considered as an extremely exciting discovery even at that time as the corresponding paper was translated from the Swedish into French and included under the title ‘‘Sur la Mine de Plomb ou Molybdène’’ in the series of ‘‘Observations sur la Physique, sur l’Histoire Naturelle et sur les Arts’’ by M. L’Abbé Rozier and M. J. A. Mongez le jeune, which collected important scientific publications of the time. Some time later, in 1826, Berzelius described the yellow precipitate that is produced when ammonium molybdate is added in excess to phosphoric acid, which is now known as the textbook example (NH4)3[PMo12O40]aq. Since this time the advances have been growing at an ever increasing rate. Polyoxometalates, a class of soluble metal oxides occupying a middle region between the monomeric metalates and the infinite metal-oxides, span a wide range of size, nuclearity, composition and physical properties that is quite breathtaking. In addition, the related research is highly interdisciplinary. The developments in polyoxometalate chemistry have been particularly remarkable and rapid since the early 1980s, facilitated by developments in instrumental analytics, and characterized by the explosion in published structural data whereby many hundreds, if not thousands, of new polyoxometalate clusters are added to the literature every year. So, what represents the state of the art, and what are the options for the future? This themed issue of Chemical Society Reviews dedicated to Polyoxometalate Cluster Science answers these questions a School of Chemistry, WestCHEM, University of Glasgow, Glasgow, G12 8QQ, UK. E-mail: lee.cronin@glasgow.ac.uk b Fakultät für Chemie, Universität Bielefeld, Postfach 100131, 33501 Bielefeld, Germany. E-mail: a.mueller@uni-bielefeld.de w Part of a themed issue covering the latest developments in polyoxometalate science.

Reduze 2 - Distributed Feynman Integral Reduction

Abstract: Reduze is a computer program for reducing Feynman integrals to master integrals employing a variant of Laporta's reduction algorithm. This article describes version 2 of the program. New features include the distributed reduction of single topologies on multiple processor cores. The parallel reduction of different topologies is supported via a modular, load balancing job system. Fast graph and matroid based algorithms allow for the identification of equivalent topologies and integrals.

GABI-Kat SimpleSearch: new features of the Arabidopsis thaliana T-DNA mutant database

Abstract: T-DNA insertion mutants are very valuable for reverse genetics in Arabidopsis thaliana. Several projects have generated large sequence-indexed collections of T-DNA insertion lines, of which GABI-Kat is the second largest resource worldwide. User access to the collection and its Flanking Sequence Tags (FSTs) is provided by the front end SimpleSearch (http://www.GABI-Kat.de). Several significant improvements have been implemented recently. The database now relies on the TAIRv10 genome sequence and annotation dataset. All FSTs have been newly mapped using an optimized procedure that leads to improved accuracy of insertion site predictions. A fraction of the collection with weak FST yield was re-analysed by generating new FSTs. Along with newly found predictions for older sequences about 20 000 new FSTs were included in the database. Information about groups of FSTs pointing to the same insertion site that is found in several lines but is real only in a single line are included, and many problematic FST-to-line links have been corrected using new wet-lab data. SimpleSearch currently contains data from � 71 000 lines with predicted insertions covering 62.5% of the 27 206 nuclear protein coding genes, and offers insertion allele-specific data from 9545 confirmed lines that are available from the Nottingham Arabidopsis Stock Centre.

(S)he's Got the Look: Gender Stereotyping of Robots1

Abstract: Previous research on gender effects in robots has largely ignored the role of facial cues. We fill this gap in the literature by experimentally investigating the effects of facial gender cues on stereotypical trait and application ascriptions to robots. As predicted, the short-haired male robot was perceived as more agentic than was the long-haired female robot, whereas the female robot was perceived as more communal than was the male counterpart. Analogously, stereotypically male tasks were perceived more suitable for the male robot, relative to the female robot, and vice versa. Taken together, our findings demonstrate that gender stereotypes, which typically bias social perceptions of humans, are even applied to robots. Implications for design-related decisions are discussed. jasp_937 2213..2230 Imagine the following scenario that takes place several decades in the future: By then, both authors of this work might be senior citizens, and the same might hold true for our readers. In spite of grieving lost youth, however, imagine that each senior citizen of this future society would be equipped with a personal robot assistant that would take care of everyday life chores, such as personal care, household maintenance, and other conveniences for you. Your personal robot assistant would facilitate everyday life by being able to support you in any possible way. What could your robot assistant look like, and why did designers opt for this particular appearance? Would your companion’s look affect your perceptions of its “personality” and capabilities? The present research focuses on exactly these questions, as we address the issues of design choices in robots and their consequences for the perception of those robots. It is clear that, to date, the scenario outlined here has not yet been fully realized. Nevertheless, taking into account the interdisciplinary effort of international scientists in social robotics, engineering, computer sciences, psychology, and related fields, such a vision will sooner or later become

Fluctuations and Correlations of net baryon number, electric charge, and strangeness: A comparison of lattice QCD results with the hadron resonance gas model

Abstract: We calculate the quadratic fluctuations of net baryon number, electric charge and strangeness as well as correlations among these conserved charges in ($2+1$)-flavor lattice QCD at zero chemical potential. Results are obtained using calculations with tree-level improved gauge and the highly improved staggered quark actions with almost physical light and strange quark masses at three different values of the lattice cutoff. Our choice of parameters corresponds to a value of 160 MeV for the lightest pseudoscalar Goldstone mass and a physical value of the kaon mass. The three diagonal charge susceptibilities and the correlations among conserved charges have been extrapolated to the continuum limit in the temperature interval $150\text{ }\text{ }\mathrm{MeV}\ensuremath{\le}T\ensuremath{\le}250\text{ }\text{ }\mathrm{MeV}$. We compare our results with the hadron resonance gas (HRG) model calculations and find agreement with HRG model results only for temperatures $T\ensuremath{\lesssim}150\text{ }\text{ }\mathrm{MeV}$. We observe significant deviations in the temperature range $160\text{ }\text{ }\mathrm{MeV}\ensuremath{\lesssim}T\ensuremath{\lesssim}170\text{ }\text{ }\mathrm{MeV}$ and qualitative differences in the behavior of the three conserved charge sectors. At $T\ensuremath{\simeq}160\text{ }\text{ }\mathrm{MeV}$ quadratic net baryon number fluctuations in QCD agree with HRG model calculations, while the net electric charge fluctuations in QCD are about 10% smaller and net strangeness fluctuations are about 20% larger. These findings are relevant to the discussion of freeze-out conditions in relativistic heavy ion collisions.

Freeze-Out Conditions in Heavy Ion Collisions from QCD Thermodynamics

Abstract: We present a determination of chemical freeze-out conditions in heavy ion collisions based on ratios of cumulants of net electric charge fluctuations. These ratios can reliably be calculated in lattice QCD for a wide range of chemical potential values by using a next-to-leading order Taylor series expansion around the limit of vanishing baryon, electric charge and strangeness chemical potentials. From a computation of up to fourth order cumulants and charge correlations we first determine the strangeness and electric charge chemical potentials that characterize freeze-out conditions in

Local Charge and Spin Currents in Magnetothermal Landscapes

Abstract: A scannable laser beam is used to generate local thermal gradients in metallic (Co2FeAl) or insulating (Y3Fe5O12) ferromagnetic thin films. We study the resulting local charge and spin currents that arise due to the anomalous Nernst effect (ANE) and the spin Seebeck effect (SSE), respectively. In the local ANE experiments, we detect the voltage in the Co2FeAl thin film plane as a function of the laser-spot position and external magnetic field magnitude and orientation. The local SSE effect is detected in a similar fashion by exploiting the inverse spin Hall effect in a Pt layer deposited on top of the Y3Fe5O12. Our findings establish local thermal spin and charge current generation as well as spin caloritronic domain imaging.

Relationships between food consumption and living arrangements among university students in four European countries - A cross-sectional study

Abstract: The transition of young people from school to university has many health implications. Food choice at the university can differ because of childhood food consumption patterns, sex and the living arrangements. Food consumption may change especially if students are living away from home. We aimed to assess food consumption patterns among university students from four European countries and how they differ by their living arrangements. We analysed data from a cross-country survey assessing health and health behaviours of students. The sample comprised a total of 2402 first year undergraduate students from one university in each of the countries of Germany, Denmark, Poland and Bulgaria. Food consumption was assessed by means of a food frequency questionnaire with 9 food groups (indicators). Students’ food consumption patterns differed across the countries. Frequent consumption of unhealthy items was common. Bulgarian students reported most often frequent consumption of sweets and cakes and snacks (e.g. chips and fast food). Polish students reported the least frequent consumption of vegetables and a low consumption of fruits. Across all countries except Bulgaria, men reported substantially more often frequent consumption of snacks than women. Students living at parental home consumed more fruit, vegetables, and meat than those who resided outside of their family home in all studied countries. There was more variation with regard to cakes and salads with more frequent consumption of cakes among Bulgarian female students and Danish male students and more frequent consumption of salads among Danish female students not living at parental home, compared to students from other countries. Nutrition habits of university students differed across countries and by sex. Students living at parental home displayed more healthy nutrition habits, with some exceptions.

“Too Many betas do not Spoil the Broth”: The Role of Beta Brain Oscillations in Language Processing

Abstract: Over the past 20 years, brain oscillations have proven to be a gateway to the understanding of cognitive processes. It has been shown that different neurocognitive aspects of language processing are associated with brain oscillations at various frequencies. Frequencies in the beta range (13-30 Hz) turned out to be particularly important with respect to cognitive and linguistic manipulations during language processing. Beta activity has been involved in higher-order linguistic functions such as the discrimination of word categories and the retrieval of action semantics as well as semantic memory, and syntactic binding processes, which support meaning construction during sentence processing. From a neurophysiological point of view, the important role of the beta frequencies for such a complex cognitive task as language processing seems reasonable. Experimental evidence suggests that frequencies in the beta range are ideal for maintaining and preserving the activity of neuronal assemblies over time. In particular, recent computational and experimental evidence suggest that beta frequencies are important for linking past and present input and the detection of novelty of stimuli, which are essential processes for language perception as well as production. In addition, the beta frequency’s role in the formation of cell assemblies underlying short-term memory seems indispensable for language analysis. Probably the most important point is the well-known relation of beta oscillations with motor processes. It can be speculated that beta activities reflect the close relationship between language comprehension and motor functions, which is one of the core claims of current theories on embodied cognition. In this article, the importance of beta oscillations for language processing is reviewed based both on findings in psychophysiological and neurophysiological literature.

Complex heavy-quark potential at finite temperature from lattice QCD.

Abstract: We calculate for the first time the complex potential between a heavy quark and antiquark at finite temperature across the deconfinement transition in lattice QCD. The real and imaginary part of the potential at each separation distance r is obtained from the spectral function of the thermal Wilson loop. We confirm the existence of an imaginary part above the critical temperature TC, which grows as a function of r and underscores the importance of collisions with the gluonic environment for the melting of heavy quarkonia in the Quark-Gluon-Plasma. Heavy-quark bound states (Q ¯ Q) are essential tools in the experimental and theoretical investigation of the high temperature state of QCD matter, the Quark-Gluon Plasma (QGP) [1]. In particular, the suppression of heavy quarkonia, as has been measured e.g. for J/

Catalytic oxidation of VOCs over mixed Co-Mn oxides

Abstract: This work reports the synthesis and characterization of single-phase cobalt manganese oxide (CMO) spinels Co3−xMnxO4 (0 ≤ x ≤ 0.34) prepared by the pulsed-spray evaporation chemical vapor deposition (PSE–CVD) method. Structure and cationic distribution of the obtained films were characterized by XRD, FTIR, XPS and Raman spectroscopy. Temperature-programmed reduction/re-oxidation (TPR/TPO) was used to elucidate the redox properties of the deposited films. The electrical resistivity was measured in the temperature range of 27–450 °C. XRD, FTIR and Raman spectra reveal the formation of single-phase cubic spinel structures up to x = 0.34. With the substitution of cobalt cations with Mn3+ and Mn4+ ions, the unit cell of the cubic spinel shows a linear increase; the TPR results indicate a lower reducibility while the TPO results display no evident change; also, the ratio Co3+/Co2+ decreased and both electrical resistivity and thermal stability showed increasing trends. The observed behavior is attributed to the progressive incorporation of manganese, which induces structural defects favoring the formation of anionic vacancies and the restriction of the oxygen mobility. The catalytic activities of the doped spinels were investigated for the deep oxidation of unsaturated hydrocarbons (C2H2 and C3H6). The introduction of a slight amount of manganese shifted the light-off curves toward lower temperatures. Based on the XPS results, the enhanced catalytic activity is thought to benefit from the abundant presence of oxygen vacancies in the doped oxide.

'If you sound like me, you must be more human': on the interplay of robot and user features on human-robot acceptance and anthropomorphism

Abstract: In an experiment we manipulated a robot's voice in two ways: First, we varied robot gender; second, we equipped the robot with a human-like or a robot-like synthesized voice. Moreover, we took into account user gender and tested effects of these factors on human-robot acceptance, psychological closeness and psychological anthropomorphism. When participants formed an impression of a same-gender robot, the robot was perceived more positively. Participants also felt more psychological closeness to the same-gender robot. Similarly, the same-gender robot was anthropomorphized more strongly, but only when it utilized a human-like voice. Results indicate that a projection mechanism could underlie these effects.

Humidity-dependent phase state of SOA particles from biogenic and anthropogenic precursors

Abstract: . The physical phase state (solid, semi-solid, or liquid) of secondary organic aerosol (SOA) particles has important implications for a number of atmospheric processes. We report the phase state of SOA particles spanning a wide range of oxygen to carbon ratios (O / C), used here as a surrogate for SOA oxidation level, produced in a flow tube reactor by photo-oxidation of various atmospherically relevant surrogate anthropogenic and biogenic volatile organic compounds (VOCs). The phase state of laboratory-generated SOA was determined by the particle bounce behavior after inertial impaction on a polished steel substrate. The measured bounce fraction was evaluated as a function of relative humidity and SOA oxidation level (O / C) measured by an Aerodyne high resolution time of flight aerosol mass spectrometer (HR-ToF AMS). The main findings of the study are: (1) biogenic and anthropogenic SOA particles are found to be amorphous solid or semi-solid based on the measured bounced fraction (BF), which was typically higher than 0.6 on a 0 to 1 scale. A decrease in the BF is observed for most systems after the SOA is exposed to relative humidity of at least 80% RH, corresponding to a RH at impaction of 55%. (2) Long-chain alkanes have a low BF (indicating a "liquid-like", less viscous phase) particles at low oxidation levels (BF

Charmonium properties in hot quenched lattice QCD

Abstract: We study the properties of charmonium states at finite temperature in quenched QCD on large and fine isotropic lattices. We perform a detailed analysis of charmonium correlation and spectral functions both below and above ${T}_{c}$. Our analysis suggests that both $S$ wave states ($J/\ensuremath{\psi}$ and ${\ensuremath{\eta}}_{c}$) and $P$ wave states (${\ensuremath{\chi}}_{c0}$ and ${\ensuremath{\chi}}_{c1}$) disappear already at about $1.5{T}_{c}$. The charm diffusion coefficient is estimated through the Kubo formula and found to be compatible with zero below ${T}_{c}$ and approximately $1/\ensuremath{\pi}T$ at $1.5{T}_{c}\ensuremath{\lesssim}T\ensuremath{\lesssim}3{T}_{c}$.

Global threats to pinnipeds

Abstract: The 2008 IUCN (International Union for Conservation of Nature) review of the status of the world’s mammals identified marine mammals (IUCN 2008) as disproportionally threatened and data poor compared to their terrestrial counterparts, and their status was noted as a particular concern (IUCN 2008, Mace et al. 2008, Schipper et al. 2008). The threats faced by marine mammals were identified as being different, with accidental mortality and pollution being dominant threats that superseded habitat loss, which was identified as the principal concern for land mammals. It was suggested that harvesting remained a major threat for half of the marine mammal species in the world. The distribution of marine mammals was described as being concentrated in tropical and temperate coastal platforms and associated with high levels of primary productivity. Threat levels were highest for marine mammals living in the North Atlantic, North Pacific and Southeast Asia. Range size was described as generally declining toward both poles. Although these generalities are of course correct for all marine mammals, it must be recognized that the larger number of species of cetaceans compared to other marine mammal groups (85 cetaceans, the polar bear Ursus maritimus, 4 extant sirenians and 36 pinniped species) biases the conclusions in the assessment for marine mammals to such a degree that a separate summary for the pinnipeds of the world is warranted. Additionally, a species-level assessment masks some important conservation concerns for pinnipeds with species classified as Least Concern actually containing threatened subspecies ( e.g., ringed seals). Finally, and perhaps most importantly, climate change issues were not specifically addressed in the vast majority of marine mammal assessments done for the 2008 IUCN review (IUCN 2008). We present here a complete assessment of the status and threats facing pinnipeds at the subspecies level, integrating the expected impacts of changing patterns of threat due to global climate change.

Left or right? Sources of political orientation: the roles of genetic factors, cultural transmission, assortative mating, and personality

Abstract: In this study, we used an extended twin family design to investigate the influences of genetic and cultural transmission as well as different sources of nonrandom mating on 2 core aspects of political orientation: acceptance of inequality and rejecting system change. In addition, we studied the sources of phenotypic links between Big Five personality traits and political beliefs using self- and other reports. Data of 1,992 individuals (224 monozygotic and 166 dizygotic twin pairs, 92 unmatched twins, 530 spouses of twins, 268 fathers, and 322 mothers) were analyzed. Genetically informative analyses showed that political attitudes are genetically but not environmentally transmitted from parents to offspring and that a substantial proportion of this genetic variance can be accounted for by genetic variance in personality traits. Beyond genetic effects and genotypic assortative mating, generation-specific environmental sources act to increase twins' and spouses' resemblance in political beliefs. The results suggest multiple sources of political orientations in a modern democracy.

The memristive magnetic tunnel junction as a nanoscopic synapse-neuron system.

Abstract: Memristors cover a gap in the capabilities of basic electronic components by remembering the history of the applied electric potentials, and are considered to bring neuromorphic computers closer by imitating the performance of synapses.[1–3] We used memristive magnetic tunnel junctions[4,5] based on MgO to demonstrate that the synaptic functionality is complemented by neuron-like behavior in these nanoscopic devices. The synaptic functionality originates in a resistance change caused by a voltage-driven oxygen vacancy motion[6] within the MgO layer. The additional functionality provided by magnetic electrodes enabled a current-driven resistance modulation due to spin-transfer torque.[7] We showed that a phenomenon known as back-hopping[8–11] leads to repeated switching between two resistance levels accompanied by current spiking, which emulates neuronal behavior. As a result, this remarkably simple system, which is composed of two magnetic layers separated by an insulator, provides a sufficient basis for the fabrication of a complete neural network. According to a simple model, the human brain consists of a network of neurons, axons and synapses. Neurons exchange electrical impulses (i.e., spikes) along their axons, and synapses are the functionalized junctions between axons and neurons. The structure of the network is defined by the spatial arrangement of neurons and axons and by the strength of each synaptic connection. In this framework, one can equate the current configuration of the network with “knowledge” and its modulation with “learning”. In the conventional (Hebbian) concept of learning,[12] synaptic strength is modified by the coincident activity of presynaptic and postsynaptic neurons. In the past few years, a series of experiments has revealed a new picture. These studies suggest that instead of mere coincidence, the precise timing of presynaptic and postsynaptic spikes (i.e., spike-timing-dependent plasticity, STDP) plays a decisive role in determining the type of synaptic modification.[13,14] This modification can lead to a persistent increase or decrease in synaptic strength, commonly referred to as long-term potentiation (LTP) or long-term depression (LTD). Software inspired by neuronal networks is widely used for specific tasks, such as pattern recognition. In addition, hardware

The Importance of Being Exchanged: [GdIII4MII8(OH)8(L)8(O2CR)8]4+ Clusters for Magnetic Refrigeration

Abstract: One of the most promising applications for molecules built from paramagnetic metal ions is low temperature magnetic refrigeration.[1] Indeed recent studies have suggested that molecular coolers can outperform any conventionally-employed solid-state refrigerant material by orders of magnitude.[2] In order to do so, molecules must possess a combination of a large spin ground state (S), with negligible anisotropy (Dcluster = 0), weak magnetic exchange between the constituent metal ions and a relatively large metal:non-metal mass ratio (i.e. a large magnetic density).[1b] These molecular pre-requisites suggest the use of lanthanide ions and, in particular, the f7 ion Gd3+ in the construction of homoand heterometallic (Gd-3d) clusters, and a sensible starting point is the synthesis of GdIII-CuII clusters since previous studies have shown this combination favours ferromagnetic exchange.[3] Here we introduce a rather remarkable new family of compounds of general formula [Ln4M8(OH)8(L)8(O2CR)8](X)4 in which almost all the constituent parts – the lanthanide ions (Ln3+), the transition metal ions (M2+), the bridging ligand L, the carboxylates and the counter anions (X) can be exchanged. In each case the structure remains essentially the same and this allows for a thorough understanding of the individual contributions to the magneto-caloric effect (MCE). In this communication we describe the three family members [Gd4M8(OH)8(L)8(O2CR)8](ClO4)4 (M = Zn, R = CHMe2, 1; M = Cu, R = CHMe2, 2; M = Ni, R = CH2Me, 3; LH = 2(hydroxymethyl)pyridine) and show how the identity of the transition metal and the sign of the magnetic exchange are vital components to consider when designing molecular coolers. For the sake of brevity we provide a generic structure description, highlighting any differences. The core (Figure 1 shows complex 2) of the molecule consists of a square (or wheel) of four cornersharing {Gd2M2O4} cubanes. The shared corners are the Gd ions which thus themselves form an inner {Gd4} square, each edge of which is occupied by two μ3-OH ions which further bridge to a MII ion. The μ3-L ions chelate the M2+ ions and use their O-arm to further bridge to the second M2+ ion in the same cubane and to one Gd ion. There are two carboxylates per cubane, each μ-bridging across a M2+...Gd square face, alternately above and below the plane of the {Gd4} square.