Dielectric Properties of Nanoconfined Water: A Canonical Thermopotentiostat Approach

We introduce a novel approach to sample the canonical ensemble at constant temperature and applied electric potential. Our approach can be straightforwardly implemented into any density-functional theory code. Using thermopotentiostat molecular dynamics simulations allows us to compute the dielectric constant of nanoconfined water without any assumptions for the dielectric volume. Compared to the commonly used approach of calculating dielectric properties from polarization fluctuations, our thermopotentiostat technique reduces the required computational time by 2 orders of magnitude.

Positive and negative emotions predict weight loss intentions and behaviors beyond theory of planned behavior constructs

PURPOSE

The current study examined the predictive utility of emotional valence (i.e., positive and negative emotions) on weight loss intentions and behaviors, beyond theory of planned behavior constructs (i.e., attitude, subjective norm, and perceived control), among a community sample of people who were overweight (BMI > 25 kg/m²).

METHODS

Participants were recruited for a longitudinal study via an online panel. They completed a baseline survey (N = 732) and a follow-up survey 6 months later (N = 526), both administered online. The surveys included measures of attitude, subjective norms, perceived control, positive and negative emotions regarding one's current weight, intentions to engage in weight loss behaviors (time 1), and having engaged in weight loss behaviors in the past 6 months (time 2).

RESULTS

Emotion explained additional variance in weight loss intentions (range ΔR² = 0.03-0.10, all ps < 0.01) and behaviors (range ΔR² = 0.01-0.02, all ps < 0.05) beyond theory of planned behavior constructs. Negative emotions mainly predicted the intake of unhealthy food and seeking social support, whereas positive emotions predicted physical activity (intention and behavior). These results suggested that the differential relations might be based on whether the strategy is approach or avoidance oriented.

CONCLUSIONS

Based on these findings, comprehensive models of weight loss behaviors should consider emotion, and the valence of such emotion, regarding current weight.

LEVEL OF EVIDENCE

Level IV, multiple time series without intervention.

Role of hole confinement in the recombination properties of InGaN quantum structures

We study the isolated contribution of hole localization for well-known charge carrier recombination properties observed in conventional, polar InGaN quantum wells (QWs). This involves the interplay of charge carrier localization and non-radiative transitions, a non-exponential decay of the emission and a specific temperature dependence of the emission, denoted as “s-shape”. We investigate two dimensional In_0.25Ga_0.75N QWs of single monolayer (ML) thickness, stacked in a superlattice with GaN barriers of 6, 12, 25 and 50 MLs. Our results are based on scanning and high-resolution transmission electron microscopy (STEM and HR-TEM), continuous-wave (CW) and time-resolved photoluminescence (TRPL) measurements as well as density functional theory (DFT) calculations. We show that the recombination processes in our structures are not affected by polarization fields and electron localization. Nevertheless, we observe all the aforementioned recombination properties typically found in standard polar InGaN quantum wells. Via decreasing the GaN barrier width to 6 MLs and below, the localization of holes in our QWs is strongly reduced. This enhances the influence of non-radiative recombination, resulting in a decreased lifetime of the emission, a weaker spectral dependence of the decay time and a reduced s-shape of the emission peak. These findings suggest that single exponential decay observed in non-polar QWs might be related to an increasing influence of non-radiative transitions.

A rare-earth free magnesium alloy with improved intrinsic ductility

Metals are the backbone of manufacturing owing to their strength and formability. Compared to polymers they have high mass density. There is, however, one exception: magnesium. It has a density of only 1.7 g/cm³, making it the lightest structural material, 4.5 times lighter than steels, 1.7 times lighter than aluminum, and even slightly lighter than carbon fibers. Yet, the widespread use of magnesium is hampered by its intrinsic brittleness. While other metallic alloys have multiple dislocation slip systems, enabling their well-known ductility, the hexagonal lattice of magnesium offers insufficient modes of deformation, rendering it intrinsically brittle. We have developed a quantum-mechanically derived treasure map which screens solid solution combinations with electronic bonding, structure and volume descriptors for similarity to the ductile magnesium-rare earth alloys. Using this insight we synthesized a surprisingly simple, compositionally lean, low-cost and industry-compatible new alloy which is over 4 times more ductile and 40% stronger than pure magnesium. The alloy contains 1 wt.% aluminum and 0.1 wt.% calcium, two inexpensive elements which are compatible with downstream recycling constraints.

Strong intermolecular antiferromagnetic verdazyl-verdazyl coupling in the solid state

Strong magnetic couplings are generally observed intramolecularly in organic diradicals or in systems in which they are promoted by crystal engineering strategies involving, for example, transition metal ligation. We herein present a strong intermolecularly coupling verdazyl radical in the solid state without the use of such design strategies. The crystal structure of an acetylene-substituted verdazyl radical shows a unique antiparallel face-to-face orientation of the neighboring verdazyl molecules along with verdazyl-acetylene interactions giving rise to an alternating antiferromagnetic Heisenberg chain. Single crystal structural data at 80, 100, 173, and 223 K show that one of the π-stacking distances depends on temperature, while heat capacity data indicate the absence of a phase transition. Based on this structural input, broken symmetry DFT calculations predict a change from an alternating linear Heisenberg chain with two comparable coupling constants J₁ and J₂ at higher temperatures towards dominant pair interactions at lower temperatures. The predicted antiferromagnetic coupling is confirmed experimentally by magnetic susceptibility, solid-state EPR and NMR spectroscopic results.

The HER2 phenotype of circulating tumor cells in HER2-positive early breast cancer: A translational research project of a prospective randomized phase III trial

Background

HER2 is one of the predominant therapeutic targets in breast cancer. The metastatic selection process may lead to discrepancies between the HER2 status of the primary tumor and circulating tumor cells (CTCs). This study analyzed the HER2 status of CTCs in patients with HER2-positive primary breast cancer at the time of diagnosis. Aim of the study was to assess potential discordance of HER2 status between primary tumor and CTCs, as this may have important implications for the use of HER2-targeted therapy.

Methods

The number and HER2 status of CTCs out of 30ml peripheral blood were assessed in 642 patients using the CellSearch System (Janssen Diagnostics, USA). The cutoff for CTC positivity was the presence of at least 1 CTC, and the cutoff for HER2 positivity of CTCs was the presence of at least 1 CTC with a strong HER2 staining.

Results

258 (40.2%) of the 642 patients were positive for CTCs (median 2; range 1–1,689). 149 (57.8%) of these 258 patients had at least 1 CTC with strong HER2 staining. The presence of HER2-positive CTCs was not associated with tumor size (p = 0.335), histopathological grading (p = 0.976), hormone receptor status (ER: p = 0.626, PR: p = 0.263) or axillary lymph node involvement (p = 0.430). Overall, 83 (32.2%) of the CTC-positive patients exclusively had CTCs with strong HER2 staining, whereas 31 (12.0%) had only CTCs with negative HER2 staining. Within-sample variation in the HER2 status of CTCs was found in 86 (57.8%) of the 149 patients with more than 1 CTC.

Conclusion

This study demonstrated that discordance between the HER2 expression of CTCs and that of the primary tumor frequently occurs in early breast cancer. Future follow-up evaluation will assess whether this discrepancy may contribute to trastuzumab resistance.

The impact of carbon and oxygen in alpha-titanium: ab initio study of solution enthalpies and grain boundary segregation

The solution, grain boundary (GB) segregation, and co-segregation of carbon and oxygen atoms in α-titanium are studied using density functional theory. For five titanium tilt boundaries, including T1, T2, and C1 twin systems, we determine the GB structure, as well as GB energy and excess volume. The segregation energies and volumes of carbon and oxygen are calculated for 23 inequivalent interstitial voids, while for co-segregation 75 configurations are considered. It is obtained that depending on the type of the segregation void both a positive and a negative segregation process is possible. The physical reasons of segregation are explained in terms of the analysis of the void atomic geometry, excess volume and features of the electronic structure at the Fermi level. Although carbon and oxygen show qualitatively similar properties in α-Ti, several distinctions are observed for their segregation behavior and mutual interactions.

Ab initio Prediction of Martensitic and Intermartensitic Phase Boundaries in Ni-Mn-Ga

Despite the importance of martensitic transformations of Ni-Mn-Ga Heusler alloys for their magnetocaloric and shape-memory properties, the martensitic part of their phase diagrams is not well determined. Using an ab initio approach that includes the interplay of lattice and vibrational degrees of freedom we identify an intermartensitic transformation between a modulated and a nonmodulated phase as a function of excess Ni and Mn content. Based on an evaluation of the theoretical findings and experimental x-ray diffraction data for Mn-rich alloys, we are able to predict the phase diagram for Ni-rich alloys. In contrast to other mechanisms discussed for various material systems in the literature, we herewith show that the intermartensitic transformation can be understood solely using thermodynamic concepts.

Understanding Anharmonicity in fcc Materials: From its Origin to ab initio Strategies beyond the Quasiharmonic Approximation

We derive the Gibbs energy including the anharmonic contribution due to phonon-phonon interactions for an extensive set of unary fcc metals (Al, Ag, Au, Cu, Ir, Ni, Pb, Pd, Pt, Rh) by combining density-functional-theory (DFT) calculations with efficient statistical sampling approaches. We show that the anharmonicity of the macroscopic system can be traced back to the anharmonicity in local pairwise interactions. Using this insight, we derive and benchmark a highly efficient approach which allows the computation of anharmonic contributions using a few T=0 K DFT calculations only.

Temperature dependent magnon-phonon coupling in bcc Fe from theory and experiment

An ab initio based framework for quantitatively assessing the phonon contribution due to magnon-phonon interactions and lattice expansion is developed. The theoretical results for bcc Fe are in very good agreement with high-quality phonon frequency measurements. For some phonon branches, the magnon-phonon interaction is an order of magnitude larger than the phonon shift due to lattice expansion, demonstrating the strong impact of magnetic short-range order even significantly above the Curie temperature. The framework closes the previous simulation gap between the ferro- and paramagnetic limits.

Phase-field modeling of grain-boundary premelting using obstacle potentials

We investigate the multiorder parameter phase field model of Steinbach and Pezzolla [Physica D 134, 385 (1999)] concerning its ability to describe grain boundary premelting. For a single order parameter situation solid-melt interfaces are always attractive, which allows us to have (unstable) equilibrium solid-melt-solid coexistence above the bulk melting point. The temperature-dependent melt layer thickness and the disjoining potential, which describe the interface interaction, are affected by the choice of the thermal coupling function and the measure to define the amount of the liquid phase. Due to the strictly finite interface thickness the interaction range also is finite. For a multiorder parameter model we find either purely attractive or purely repulsive finite-ranged interactions. The premelting transition is then directly linked to the ratio of the grain boundary and solid-melt interfacial energy.

Doping of AlGaN Alloys

Nitride-based device structures for electronic and optoelectronic applications usually incor-porate layers of AlxGa1−xN, and n- and p-type doping of these alloys is typically required. Experimental results indicate that doping efficiencies in AlxGa1−xN are lower than in GaN. We address the cause of these doping difficulties, based on results from first-principles density-functional-pseudopotential calculations. For n-type doping we will discuss doping with oxygen, the most common unintentional donor, and with silicon. For oxygen, a DX transition occurs which converts the shallow donor into a negatively charged deep level. We present experimental evidence that oxygen is a DX center in AlxGa1−xN for x>∼0.3. For p-type doping, we find that compensation by nitrogen vacancies becomes increasingly important as the Al content is in-creased. We also find that the ionization energy of the Mg acceptor increases with alloy composition x. To address the limitations on p-type doping we have performed a comprehensive investigation of alternative acceptor impurities; none of the candidates exhibits characteristics that surpass those of Mg in all respects.

Abstract P1-04-06: Discordance of the ER- and HER2-status on disseminated tumor cells compared to the primary tumor in patients with early breast cancer

Background: Differences in ER- and HER2-expression on metastases compared to the primary tumor (PT) are a known phenomenon and may have clinical implications in respect of targeted systemic treatment approaches. The aim of this study was to evaluate both ER- and HER2-status on disseminated tumor cells (DTCs) in the bone marrow (BM) of patients (pts) with early breast cancer (EBC) and to compare these with the corresponding PT.

Methods: BM aspirates were obtained at the time of first surgery. After Ficoll enrichment for mononuclear cells two cytospins with 106 BM cells were evaluated for ER-, HER2- and cytokeratin (CK) -expressions simultaneously by immunocytochemistry using a triple fluorescence staining method with antibodies directed against human ER (secondly labeled with Cy3, red), HER2 (Coumarin-AMCA, blue) and CK (DyLight488, green). The manual analysis was conducted using a computerized fluorescence microscope (Axioskop, Zeiss, Germany). Criteria for CK- and HER2-positivity were the ring-like appearance of the respective membrane stainings and for ER-expression a nuclear staining. Only pts with the detection of CK positive cells (DTC+) and known ER- and HER2-status of the PT (n = 54) were selected for this analysis.

Results: The median number of DTCs was 13 (range 1-95; total number of DTCs detected: 1082). 40 (74%) of the pts had at least one ER-positive (pos) DTC, 24 (44%) at least one HER2-pos DTC, 14 (26%) at least one ER-pos/HER2-pos DTC, and 50 (93%) at least one ER-negative/HER2-negative (neg) DTC, while 10 (19%) pts had only ER-neg/HER2-neg DTCs.

The concordance rate between ER-status on DTCs and PT was 74%. Pts with an ER-pos PT were significantly more likely to have at least one ER-pos DTC (34 out of 42) than pts with an ER-neg PT (6 out of 12; Chi-square test, χ2 = 4.66, p = 0.031). 39 (93%) of the 42 pts with ER-pos PT had at least 1 ER-neg DTC.

The concordance rate between HER2-status on DTCs and PT was 52%. The probability of having at least one HER2-pos DTC was not related to the HER2-status of the PT (Chi-square test, χ2 = 0.34, p = 0.56). 22 (46%) of the 48 pts with a HER2-neg PT had at least one HER2-pos DTC. All of the 6 pts with a HER2-pos PT had at least one HER2-neg DTC.

7 out of 10 pts with a triple-neg PT had at least one DTC pos for ER, HER2 or both. Further the heterogeneity of the ER- and HER2-expression on DTCs compared to the PT for different DTC counts was evaluated. We detected all possible combinations of ER- and HER2-experssion on DTCs regardless of the respective status of the PT.

Conclusions: Our study confirms that the ER- and/or HER2-status on DTCs may differ compared to the PT. This discordance could be especially important for pts with a triple-neg PT and ER-pos or HER2-pos DTCs, since they might respond favorably to an endocrine or HER2-targeted therapy. On the other hand, the presence of ER-neg or HER2-neg DTCs in pts with ER-pos or HER2-pos PT might explain some of the failures of adjuvant endocrine or HER2 targeted therapy.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-04-06.

Thermodynamic modeling of chromium: strong and weak magnetic coupling

As chromium is a decisive ingredient for stainless steels, a reliable understanding of its thermodynamic properties is indispensable. Parameter-free first-principles methods have nowadays evolved to a state allowing such thermodynamic predictions. For materials such as Cr, however, the inclusion of magnetic entropy and higher order contributions such as anharmonic entropy is still a formidable task. Employing state-of-the-art ab initio molecular dynamics simulations and statistical concepts, we compute a set of thermodynamic properties based on quasiharmonic, anharmonic, electronic and magnetic free energy contributions from first principles. The magnetic contribution is modeled by an effective nearest-neighbor Heisenberg model, which itself is solved numerically exactly by means of a quantum Monte Carlo method. We investigate two different scenarios: a weak magnetic coupling scenario for Cr, as usually presumed in empirical thermodynamic models, turns out to be in clear disagreement with experimental observations. We show that instead a mixed Hamiltonian including weak and strong magnetic coupling provides a consistent picture with good agreement to experimental thermodynamic data.

Blocking growth by an electrically active subsurface layer: the effect of Si as an antisurfactant in the growth of GaN

Combining aberration corrected high resolution transmission electron microscopy and density functional theory calculations we propose an explanation of the antisurfactant effect of Si in GaN growth. We identify the atomic structure of a Si delta-doped layer (commonly called SiN(x) mask) as a SiGaN(3) monolayer that resembles a √3×√3 R30° surface reconstruction containing one Si atom, one Ga atom, and a Ga vacancy (V(Ga)) in its unit cell. Our density functional theory calculations show that GaN growth on top of this SiGaN(3) layer is inhibited by forming an energetically unfavorable electrical dipole moment that increases with layer thickness and that is caused by charge transfer between cation dangling bonds at the surface to V(Ga) bound at subsurface sites.

Abstract P2-01-11: Detection and characterization of circulating and disseminated tumour cells in blood and bone marrow of breast cancer patients by two different biochemical methods

Background: The main reason for breast cancer associated death are remote metastases, that are due to cells, that dissolve from the primary tumour, and are found in blood (circulating tumour cells, CTCs) and bone marrow (disseminated tumour cells, DTCs). The detection of these cells in breast cancer patients is mostly linked to a worse prognosis.

We present an immunohistochemical staining method for the detection of DTCs from bone marrow by using the cancer-associated Thomsen-Friedenreich antigen (TF) in combination with Her-2, and stem cell markers (Muc-1, ALDH1A1), and a highly sensitive RT-PCR based approach for CTC-detection from peripheral blood of adjuvant breast cancer patients using the established cytokeratin markers CK8, 18 and 19.

Materials and Methods: 20ml blood and 2–3ml of bone marrow were withdrawn from 20 respectively 40 primary breast cancer patients during surgery. For this investigation we used only samples of patients with at least one CTC already detected with the FDA approved VERIDEX CellSearch System.

RT PCR investigations blood samples from healthy donors were taken and used as control group.

For both methods an enrichment of mononuclear cell fraction, containing DTCs and CTCs, was carried out by density gradient centrifugation.

For immunohistochemical staining cells were spun down on coverslips fixed and stained with antibodies against Thomsen-Friedenreich-Antigen and Her-2, MUC1 or ALDH1A1.

For Real-Time PCR RNA was isolated from the cell pellet obtained by density gradient centrifugation, reversely transcribed to cDNA and RT-PCR was run with Taq-Man Primers against Cytokeratin (CK) 8, 18 and 19. The housekeeping gene 18S was used as internal reference.

Results: For the staining of Her-2 and TF, 78,01% of all samples showed at least one stained cell. The biggest subgroup within these samples was the double stained one with 46,14%.

In the other two experimental settings respectively the biggest cohorts were only single stained with TF (47,4% for TF-MUC1) or ALDH1A1 (59,65% for TF-ALDH1A1).

Within the PCR trials, the investigation between the negative control group and adjuvant breast cancer blood samples showed significant correlations for the expressions of CK8 (p &lt; 0,047) and CK18 (p &lt; 0,041). CK19 showed borderline significance (P &lt; 0,057) of correlation.

Conclusion: The immunostaining-combination of diverse cell surface antigens for detection and characterization of DTCs, especially the TF antigen, in combination with Her-2, Muc-1 and ALDH1A1 is an excellent way to detect DTC's in bone marrow due to its significant correlations (p &lt; 0.001).

The verification of CTC's by using RT-PCR is possible by using epithelial marker genes like the cytokeratins, especially CK8 and 18.

Both methods can be a step towards modern personalized medicine and lead to new ways of early tumour detection. Additionally an improved tumour characterization might ease the decision on specific medical treatment (eg against Her-2).

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P2-01-11.

Motivated shortcomings in explanation: the role of comparative self-evaluation and awareness of explanation recipient's knowledge

Being aware of someone else's existing knowledge is a prerequisite to effectively adapting an explanation to that person's learning needs. However, such knowledge awareness introduces the potential for motivated self-evaluation based on relative knowledge, that is, for social comparison. Because favorable social comparisons are actively defended, we propose that knowledge awareness might undermine information sharing in explanation when social comparison motives are active. We tested this hypothesis in a series of experiments in which participants provided explanations to an ostensible learning partner with or without knowledge awareness. Both dispositionally and situationally motivated social comparison interacted with knowledge awareness to reduce information sharing in explanation. Intriguingly, knowledge awareness uniformly facilitated adaptation of the information that was shared to address partner knowledge deficit. These results illustrate a tension in the components of effective explanation. At the same time that knowledge awareness effectively coordinates explanation content, it can lead to knowledge hoarding by knowledgeable explainers who are motivated to rely on knowledge differences between the self and the explanation recipient for self-evaluation.

Advancing density functional theory to finite temperatures: methods and applications in steel design

The performance of materials such as steels, their high strength and formability, is based on an impressive variety of competing mechanisms on the microscopic/atomic scale (e.g. dislocation gliding, solid solution hardening, mechanical twinning or structural phase transformations). Whereas many of the currently available concepts to describe these mechanisms are based on empirical and experimental data, it becomes more and more apparent that further improvement of materials needs to be based on a more fundamental level. Recent progress for methods based on density functional theory (DFT) now makes the exploration of chemical trends, the determination of parameters for phenomenological models and the identification of new routes for the optimization of steel properties feasible. A major challenge in applying these methods to a true materials design is, however, the inclusion of temperature-driven effects on the desired properties. Therefore, a large range of computational tools has been developed in order to improve the capability and accuracy of first-principles methods in determining free energies. These combine electronic, vibrational and magnetic effects as well as structural defects in an integrated approach. Based on these simulation tools, one is now able to successfully predict mechanical and thermodynamic properties of metals with a hitherto not achievable accuracy.

The influence of additions of Al and Si on the lattice stability of fcc and hcp Fe-Mn random alloys

We have studied the influence of additions of Al and Si on the lattice stability of face-centred-cubic (fcc) versus hexagonal-closed-packed (hcp) Fe-Mn random alloys, considering the influence of magnetism below and above the fcc Néel temperature. Employing two different ab initio approaches with respect to basis sets and treatment of magnetic and chemical disorder, we are able to quantify the predictive power of the ab initio methods. We find that the addition of Al strongly stabilizes the fcc lattice independent of the regarded magnetic states. For Si a much stronger dependence on magnetism is observed. Compared to Al, almost no volume change is observed as Si is added to Fe-Mn, indicating that the electronic contributions are responsible for stabilization/destabilization of the fcc phase.

Hydrogen in GaN

Hydrogen is implicated in the low doping efficiency of acceptors (e.g., Mg) in MOCVD-grown GaN by the following observations: the well-established role of hydrogen in the same phenomenon in other semiconductors; re-passivation of thermally activated Mg in GaN upon exposure to NH3 or H at temperatures > 400°C; correlation between Mg and H concentrations; and computational studies on the diffusivities of charged H in GaN and on the configuration and stability of the Mg-H complex in GaN. Strong experimental evidence for the Mg-H complex comes from variable-temperature Hall effect measurements which reveal that after hydrogenation of activated GaN:Mg the hole mobility increases as the hole concentration decreases, which is consistent with removal of ionized scattering centers and not with the introduction of separate compensating defects. However, experimental evidence is also accumulating to suggest that the Mg activation process involves the generation or transformation of electrically active defects.

CAD/CAM-produced surgical guides: Optimizing the treatment workflow

The increased availability of devices for 3D radiological diagnosis allows the more frequent use of CAD/CAM-produced surgical guides for implant placement. The conventional workflow requires a complex logistic chain which is time-consuming and costly. In a pilot study, the workflow of directly milled surgical guides was evaluated. These surgical guides were designed based on the fusion of an optical impression and the radiological data. The clinical use showed that the surgical guides could be accurately placed on the residual dentition without tipping movements. The conventional surgical guides were used as a control for the manual check of the deviation of the implant axis. The direct transfer of the digital planning data allows the fabrication of surgical guides in an external center without the need of physical transport, which reduces the logistic effort and expense of the central fabrication of surgical guides.

Quantum Chemical Calculation of Raman Intensities for Large Molecules: The Photoisomerization of [{Fe‘S4’(PR3)}2(N2H2)] (‘S4’2− = 1,2-bis(2-Mercaptophenylthio)-Ethane(2−))

Since Raman spectra of isolated large molecules are hardly accessible by present day quantum chemical methods, we demonstrate how Raman intensities for selected vibrational normal modes can be calculated by extension of a semi-numerical, very flexible approach to the calculation of vibrational spectra [see J. Neugebauer et al., J. Comp. Chem. 23 (2002) 895–910]. The methodology is applied to a Ci -symmetric dinuclear diazene iron–sulfur complex with relevance to the biological nitrogen fixation problem. The accuracy of the vibrational spectra allows us to use the spectra for structure determination and assignment of bands to isomeric structures, which were conjectured to be generated by a photoisomerization process. We can in turn support the photoisomerization hypothesis.

Understanding the phase transitions of the Ni2MnGa magnetic shape memory system from first principles

The free energies of the austenite, the (modulated) premartensite and the unmodulated martensite of Ni2MnGa are determined using density functional theory and including quasiharmonic phonons and fixed-spin-moment magnons. This approach very well reproduces the complete phase sequence (martensite<-->premartensite<-->austenite) of stoichiometric Ni2MnGa as a function of temperature. By analyzing the relevant free energy contributions, we also understand the delicate interplay of phonons and magnons driving both phase transitions.

Compositional correlation and anticorrelation in quaternary alloys: competition between bulk thermodynamics and surface kinetics

We analyze the atomistic mechanisms driving the compositional correlation of In and N in the quaternary Inx Ga1-xAs1-yNy alloys combining atomic scale chemical analysis in transmission electron microscopy and density-functional theory calculations. Our results show that for typical growth conditions surface kinetics prevail over bulk thermodynamics resulting in a hitherto unexpected compositional anticorrelation between In and N.

Intraoperative navigation in the maxillofacial area based on 3D imaging obtained by a cone-beam device

The aim of this study was to evaluate intraoperative navigation in the maxillofacial area based on three-dimensional imaging obtained by a cone-beam device. Digital volume tomograms (DVT) were obtained by the prototype of GALILEOS (Sirona Dental Systems Inc., Bensheim, Germany), a newly developed, compact size, cone-beam machine with a scan volume of 15 cm x 15 cm x 15 cm. Intraoperative navigation was performed in 12 patients in three selected indications. Target detection error expressing the accuracy of DVT navigation and registration performance of specially developed methods for image-to-patient registration was estimated. Target detection error was maximally 2 mm and depended on the registration method chosen. The automatic detection rate of the fiducial markers ranged between 0.64 and 0.32. The preoperatively defined treatment plan was fully accomplished in 11 out of 12 cases. A favourable surgical outcome was achievable in all cases. Intraoperative complications were not observed. Intraoperative navigation based on DVT imaging can be considered as a valuable alternative to CT-based procedures. Special characteristics of the cone-beam technique, in terms of contrast resolution and the limited field-of-view size of the devices, restrict the indication spectrum and create a demand for modifications of the usual registration methods.

Pimecrolimus (ELIDEL®) zur Behandlung des Lichen planus mucosae

Oral lichen planus (OLP) is a common chronic inflammatory disorder with criteria of auto-reactive disease. Treatment consists on topical application of corticosteroids, vitamin A derivates or cyclosporin. Calcineurin inhibitors as tacrolimus and pimecrolimus decrease the production of cytokines and inhibit T-cell proliferation. These substances have recently been introduced for local therapy of chronic inflammatory skin disorders. The aim of our study was to evaluate the effectiveness and side effects of local pimecrolimus in OLP. A group of five patients with histological proven OLP were treated with topical pimecrolimus 1% ointment twice daily to the affected area. Prior to treatment and after 7, 14, 28 and 42 days the lesions were assessed clinically and by photographs. The discomfort scores were evaluated by visual analogue scale (VAS) weekly. All five patients (median age 65.6 years) were female and showed involvement of the buccal mucosa. All lesions showed a reduction of inflammation activity during the treating period. The VAS scores decreased significantly under treatment (p=0,0014). Pimecrolimus ointment was tolerated well with no signs of itching or burning. However, 4 out of 5 patients complained about the reduced adherence properties of the cream. Although no complete remission of OLP has been observed in our series, signs of inflammatory activity of OLP as redness and burning sensations were reduced by topical pimecrolimus. Further controlled randomized studies have to be conducted to compare topical pimecrolimus with topical corticosteroid as standard therapy. The adherence properties of pimecrolimus 1% cream should be improved for intra-oral application.