Is silver diammine fluoride effective in arresting dental caries in cavitated primary molars?

CLINICAL QUESTION

To evaluate the efficacy of silver diamine fluoride (SDF) in arresting dental caries in cavitated caries lesions in primary molars.

DATA SOURCES

A systematic search was carried out in PubMed, Scopus, and Embase. Furthermore, cross-referencing was performed using the references lists of full-text articles and grey literature was also retrieved for eligible studies. Two independent reviewers were responsible for study selection and data extraction.

STUDY SELECTION

Randomized and non-randomized clinical studies that evaluated the caries arrest rate of SDF compared to no treatment or any other type of non-invasive or minimally-invasive treatment were included. Only publications in the English, Italian and French language and with a minimum follow-up of 6 months were considered for study eligibility.

DATA EXTRACTION AND SYNTHESIS

The characteristics of the included studies-age, sex, type of study, sample size, caries at baseline, setting, operator, blinding, intervention, outcomes and assessment of any confounders-were extracted from the included papers. The quality assessment was carried out using the Cochrane risk of bias tool. The success rate and odds ratios were chosen to calculate the effect size for the meta-analysis.

RESULTS

A total of nine publications were included for qualitative review and five of them were included in the meta-analysis. Around half of lesions that received annual or biannual application SDF ≥ 38% were arrested.

CONCLUSIONS

SDF 38% application was found to be effective in arresting dental caries progression in cavitated primary molars.

Pathways between Social Capital and Oral Health from Childhood to Adolescence

This study aimed to evaluate the theoretical pathways by which social capital can influence dental caries and oral health-related quality of life (OHRQoL) of children over time. This 10-y prospective cohort started in 2010 with a sample of 639 preschoolers aged 1 to 5 y from the southern Brazil. Community and individual social capital were assessed at baseline through the presence of formal institutions in the neighborhood and social networks, respectively. In the 10-y follow-up, the individual social capital was evaluated by social trust and social networks. Dental caries was measured by the International Caries Detection and Assessment System (ICDAS), and the short version of the Child Perception Questionnaire (CPQ11-14) was used to assess OHRQoL. Demographic, socioeconomic, behavioral (frequency of toothbrushing and use of dental services), and psychosocial (sense of coherence) characteristics were also assessed. Structural equation modeling was used to evaluate the associations between variables over time. About 429 children were reassessed at 10-y follow-up (67.1% cohort retention rate). High community social capital at baseline directly predicted lower occurrence of dental caries and better OHRQoL after 10 y. Social capital at community level also indirectly predicted lower occurrence of dental caries through sense of coherence, frequency of toothbrushing, and use of dental services. Individual social capital at follow-up was indirectly linked to OHRQoL via the psychosocial pathway (sense of coherence). Community-level social capital was associated with dental caries and OHRQoL over time. The relationship between individual social capital and oral health was mediated through the psychosocial pathway.

Structural, magnetic and electrical properties of SrRuO3 films and SrRuO3/SrTiO3 superlattices

SrRuO3 films and SrRuO3/SrTiO3 superlattices grown on SrTiO3(001) were studied by structural, magnetic, magnetoresistance and Hall effect measurements. The superlattices showed heteroepitaxial growth with coherent interfaces and a Ru/Ti diffusion region of 1-1.5 unit cells. The resistivity had metallic character above a critical thickness of 3-4 unit cells, becoming insulating below. There was no hint of conduction processes along the interfaces. Both magnetization and magnetoresistance measurements showed an increase of the magnetic anisotropy, consistent with magnetostriction effects. The magnetostriction coefficient was estimated as λ100 ∼ 1.4 × 10(-4). Three unit cell thick SrRuO3 layers in SrRuO3/SrTiO3 superlattices were found to have tetragonal crystal symmetry, as deduced from the sign change of the anomalous Hall constant.

Stabilization of ferromagnetic order in La(0.7)Sr(0.3)MnO3-SrRuO3 Superlattices

The study of spatially confined complex oxides is of wide interest, since correlated electrons at interfaces might form exotic phases. Here La(0.7)Sr(0.3)MnO(3)/SrRuO(3) superlattices with coherently grown interfaces were studied by structural techniques, magnetization, and magnetotransport measurements. Magnetization measurements showed that ferromagnetic order in ultrathin La(0.7)Sr(0.3)MnO(3) layers is stabilized in the superlattices down to layer thicknesses of at least two unit cells. This stabilization is destroyed, if the ferromagnetic layers are separated by two unit cell thick SrTiO(3) layers. The resistivity of the superlattices showed metallic behavior and was dominated by the conducting SrRuO(3) layers, the off-diagonal resistivity showed an anomalous Hall effect from both SrRuO(3) and La(0.7)Sr(0.3)MnO(3) layers. This shows that the La(0.7)Sr(0.3)MnO(3) layers are not only ferromagnetic but also highly conducting; probably a conducting hole gas is induced at the interfaces that stabilizes the ferromagnetic order. This result opens up an alternative route for the fabrication of two-dimensional systems with long-range ferromagnetic order.

Dendritic cell, monocyte and T cell activation and response to glatiramer acetate in multiple sclerosis

BACKGROUND

Treatment with glatiramer acetate (GA) modestly decreases disease activity in multiple sclerosis (MS). The mechanism of action is incompletely understood and differences in the response to treatment between individuals may exist.

OBJECTIVE

To study the activation of CD4+ T cells, monocytes and dendritic cells (DC) in relation to disease activity in MS patients treated with GA.

METHODS

Flow cytometry was used to study the activation of CD4+ T cells and T cell subsets (CD25(high) and CD26(high) cells), monocytes and DCs in a cross-sectional study of 39 untreated and 29 GA-treated MS patients, the latter followed prospectively for one year. Gd-enhanced magnetic resonance imaging (MRI) studies were conducted in all patients. Disease activity was assessed as relapses.

RESULTS

The median percentage of DCs expressing CD40 was 10% in untreated MS patients and 5.9% in GA-treated patients (Bonferroni-corrected p=0.0005). The hazard ratio of relapse was 1.32 (95% confidence interval 1.05-1.64) per 1% increase in CD40+ DCs. Patients treated with GA had fewer CD4+ T cells expressing surface markers associated with T helper type 1 effector responses and more CD4+ T cells expressing surface markers associated with regulatory, naïve or central memory T cell populations, but CD4+ T cell activation was not related with relapse risk.

CONCLUSIONS

MS patients treated with GA show prominent changes in circulating antigen-presenting cells and CD4+ T cells. Expression of CD40 on DCs is significantly lower and associated with relapse risk in MS patients treated with GA.

Reversible electrical switching of spin polarization in multiferroic tunnel junctions

Spin-polarized transport in ferromagnetic tunnel junctions, characterized by tunnel magnetoresistance, has already been proven to have great potential for application in the field of spintronics and in magnetic random access memories. Until recently, in such a junction the insulating barrier played only a passive role, namely to facilitate electron tunnelling between the ferromagnetic electrodes. However, new possibilities emerged when ferroelectric materials were used for the insulating barrier, as these possess a permanent dielectric polarization switchable between two stable states. Adding to the two different magnetization alignments of the electrode, four non-volatile states are therefore possible in such multiferroic tunnel junctions. Here, we show that owing to the coupling between magnetization and ferroelectric polarization at the interface between the electrode and barrier of a multiferroic tunnel junction, the spin polarization of the tunnelling electrons can be reversibly and remanently inverted by switching the ferroelectric polarization of the barrier. Selecting the spin direction of the tunnelling electrons by short electric pulses in the nanosecond range rather than by an applied magnetic field enables new possibilities for spin control in spintronic devices.

Glatiramer acetate antibodies, gene expression and disease activity in multiple sclerosis

BACKGROUND

Glatiramer acetate (GA) treatment suppresses disease activity in multiple sclerosis (MS). The immunological response to treatment may differ in patients who are stable on GA therapy and patients with breakthrough disease activity, but the results of previous studies are inconsistent.

OBJECTIVES

We studied the immunological response to GA and its relationship with disease activity.

METHODS

Anti-GA antibodies in plasma and the expression of genes encoding cytokines and T-cell-polarizing transcription factors in blood cells were analysed by flow cytometric bead array and polymerase chain reaction (PCR) analysis in 39 untreated and 29 GA-treated relapsing-remitting MS patients. Definition of breakthrough disease was based on the occurrence of relapses, disability progression, or gadolinium (Gd)-enhanced MRI.

RESULTS

The expression of T helper type 1 (Th1) and Th17 cytokines and transcription factors was reduced during long-term treatment, but there was no relationship between the expression of cytokines and transcription factors and anti-GA antibodies. High expression of mRNA encoding GATA3 and lymphotoxin-β (LT-β) was associated with low disease activity in Gd-enhanced MRI studies. None of the variables studied were associated with clinical disease activity. GA treatment resulted in the development of IgG and IgG4 anti-GA antibodies during the first months of treatment, persisting during long-term treatment.

CONCLUSIONS

The observed relationship between the expression of mRNA encoding GATA3 and LT-β expression and MRI disease activity deserves further analysis in future studies. The development of anti-GA antibodies was observed in all patients treated with GA, but this was not related with measures of cellular immunity, clinical or MRI disease activity.

Epitaxial Ferroelectric Aurivillius-Type Phases on Metallic Oxides by Pulsed Laser Deposition

Bi-based layered perovskites, also called Aurivillius-type phases, are superior to simple perovskite materials with regard to their ferroelectric long-term stability. Another way to alleviate fatigue and aging problems in metal-ferroelectric-metal (MFM) heterostructures is to replace the bottom metallic electrode with a conductive oxide electrode. An attempt to combine the two approaches has been made to investigate whether a further improvement in stability can be achieved. To promote an oriented growth of the ferroelectric films, epitaxial buffer layers (YSZ, Ce02) and epitaxial electrodes of (La0.5Sr0.5 )Co03 (LSC) have been consecutively deposited onto Si (100). Finally a ferroelectric thin film of the layered perovskite Bi4Ti3012 (BiT) has been grown. Rocking curve measurements demonstrate good epitaxial growth of both the buffer and the electrode layers. The ferroelectric thin films show a preferred c-axis orientation. Cross-section TEM images reveal a twinned superstructure in the LSC layer with a tripling of the lattice parameter. EDX line-scans show that a Co-enriched and Bi-depleted layer had formed at the BiT/LSC interface. After deposition of Au electrodes on both the BiT and the LSC layer, a hysteretic behavior could be detected and the ferroelectric properties of the c-oriented BiT film be confirmed.

Increased urinary orosomucoid excretion predicts preeclampsia in pregnant women with pregestational type 1 diabetes

AIMS

We evaluated the urinary orosomucoid excretion (UOE) as a biomarker of preeclampsia and preterm delivery in pregnant women with type 1 diabetes.

METHODS

Singleton pregnant women with pregestational type 1 diabetes were included provided one urine sample had been collected before 17 gestational weeks. Serum and urinary orosomucoid were analysed by immunoturbidimetry. Primary outcome measurements were development of preeclampsia (blood pressure>140/90mmHg and proteinuria) and preterm delivery before 37 weeks.

RESULTS

In total 173 women were included. The UOE increased during pregnancy. Preeclampsia developed in 20 women and 65 women delivered preterm. Using logistic regression analysis we found that UOE>1.37mg/l (OR: 6.85 (95% CI: 1.97-23.88; p<0.003)), nulliparity (3.88 (1.10-13.72); p<0.04), systolic blood pressure>120mmHg (4.12 (1.35-12.59); p<0.02) and duration of diabetes>20 years (3.69 (1.18-11.52); p<0.03) independently predicted the development of preeclampsia. Independent predictors of preterm delivery were duration of diabetes and HbA1c>7%. The remaining covariates included in the regression models were BMI, serum creatinine, smoking and microalbuminuria.

CONCLUSIONS

Increased UOE early in pregnancy predicted preeclampsia in women with pregestational type 1 diabetes independently of albuminuria and other known risk factors. No association to preterm delivery was found.

Breakthrough disease during interferon-β therapy in MS

Background: Disease activity is highly variable in patients with multiple sclerosis (MS), both untreated and during interferon (IFN)-β therapy. Breakthrough disease is often regarded as treatment failure; however, apart from neutralizing antibodies (NAbs), no blood biomarkers have been established as reliable indicators of treatment response, despite substantial, biologically measurable effects. We studied the biologic response to treatment in a cohort of NAb-negative patients to test whether difference in responsiveness could segregate patients with and without breakthrough disease during therapy.

Methods: Gene expression in blood cells from 23 patients with relapsing-remitting MS was analyzed by microarray and PCR. Samples were collected pretreatment and 9–12 hours after IFNβ injection at 3 and 6 months' treatment. Definition of breakthrough disease was based on the occurrence of relapses, disability progression, or subclinical activity on 3T MRI at 3 and 6 months.

Results: Sixteen patients had breakthrough disease and 7 patients were stable. Microarray and PCR showed marked effects of IFNβ on gene expression profiles, but biologic responses did not differ between patients with breakthrough disease and stable patients. However, pretreatment variables did differ: patients with breakthrough disease had lower baseline IL10 expression, more gadolinium-enhancing lesions, and a higher number and volume of T2 lesions.

Conclusions: Breakthrough disease during interferon (IFN)-β treatment is not paralleled by differences in biologic responsiveness to treatment in NAb-negative patients; most likely, the spontaneously occurring variation in underlying disease activity between patients causes the varying level of breakthrough disease observed in IFNβ-treated patients with multiple sclerosis.

Tailoring magnetic interlayer coupling in La0.7Sr0.3MnO3/SrRuO3 superlattices

The magnetic interlayer coupling in La0.7Sr0.3MnO3/SrRuO3 superlattices was investigated. High quality superlattices with ultrathin La0.7Sr0.3MnO3 and SrRuO3 layers were fabricated by pulsed laser deposition. The superlattices grew coherently with Mn/Ru intermixing restricted to about one interfacial monolayer. Strong antiferromagnetic interlayer coupling depended delicately on magnetocrystalline anisotropy and intermixing at interfaces. Ab initio calculations elucidated that the antiferromagnetic coupling is mediated by the Mn-O-Ru bond. The theoretical calculations allowed for a quantitative correlation between the total magnetic moment of the superlattice and the degree of Mn/Ru intermixing.

Fabrication of epitaxial nanostructured ferroelectrics and investigation of their domain structures

Nanostructured ferroelectrics are important objects for studies on ferroelectric size effects as well as for applications to memory devices with ultra-high memory density. In the present article, we introduce several approaches for the synthesis of confined ferroelectrics with sizes in and below the hundreds of nanometer range, including top-down processes like e-beam lithography, self-assembly methods like chemical solution deposition, and growth by pulsed laser deposition using stencil masks. Furthermore, the ferroelectric domain structure of part of these nanostructures is investigated by means of synchrotron X-ray diffraction, and its contribution to the ferroelectric properties is discussed.

Influence of long-range dipolar interactions on the phase stability and hysteresis shapes of ferroelectric and antiferroelectric multilayers

Phase transition and field driven hysteresis evolution of a two-dimensional Ising grid consisting of ferroelectric-antiferroelectric multilayers that take into account the long range dipolar interactions were simulated by a Monte-Carlo method. Simulations were carried out for a 1 + 1 bilayer and a 5 + 5 superlattice. Phase stabilities of components comprising the structures with an electrostatic-like coupling term were also studied. An electrostatic-like coupling, in the absence of an applied field, can drive the ferroelectric layers toward 180° domains with very flat domain interfaces mainly due to the competition between this term and the dipole-dipole interaction. The antiferroelectric layers do not undergo an antiferroelectric-to-ferroelectric transition under the influence of an electrostatic-like coupling between layers as the ferroelectric layer splits into periodic domains at the expense of the domain wall energy. The long-range interactions become significant near the interfaces. For high periodicity structures with several interfaces, the interlayer long-range interactions substantially impact the configuration of the ferroelectric layers while the antiferroelectric layers remain quite stable unless these layers are near the Neel temperature. In systems investigated with several interfaces, the hysteresis loops do not exhibit a clear presence of antiferroelectricity that could be expected in the presence of anti-parallel dipoles, i.e., the switching takes place abruptly. Some recent experimental observations in ferroelectric-antiferroelectric multilayers are discussed where we conclude that the different electrical properties of bilayers and superlattices are not only due to strain effects alone but also due to long-range interactions. The latter manifests itself particularly in superlattices where layers are periodically exposed to each other at the interfaces.

Emergency department-initiated tobacco control: a randomised controlled trial in an inner city university hospital

Objectives:

Emergency department (ED) patients show high smoking rates. The effects of ED-initiated tobacco control (ETC) on 7-day abstinence at 12 months were investigated.

Methods:

A randomised controlled intention-to-treat trial (trials registry no.: ISRCTN41527831) was conducted with 1044 patients in an urban ED. ETC consisted of on-site counselling plus up to four telephone booster sessions. Controls received usual care. Analysis was by logistic regression.

Results:

In all, 630 (60.7%) participants were males, the median age was 30 years (range 18–81) and the median smoking intensity was 15 (range 1–60) cigarettes per day. Overall, 580 study participants (55.6%) were unmotivated, 331 (31.7%) were ambivalent and 133 (12.7%) were motivated smokers. ETC (median time 30 (range 1–99) min) was administered to 472 (91.7% out of 515) randomised study participants. At follow-up, 685 study participants (65.6% of 1044) could be contacted. In the ETC group, 73 out of 515 (14.2%) in the ETC group were abstinent, whereas 60 out of 529 (11.3%) controls were abstinent (OR adjusted for age and gender = 1.31 (95% CI 0.91 to 1.89, p = 0.15). Stratified for motivation to change behaviour, the adjusted ORs for ETC versus usual care were OR = 1.00 (95% CI 0.57 to 1.76) in unmotivated smokers, respectively OR = 1.37 (95% CI 0.73 to 2.58) in ambivalent smokers and OR = 2.19 (95% CI 0.98 to 4.89) in motivated smokers, p for trend = 0.29.

Conclusions:

ETC, in the form of on-site counselling with up to four telephone booster sessions, showed no overall effect on tobacco abstinence after 12 months. A non-significant trend for a better performance of ETC in more motivated smokers was observed.

Influence of interface structure on mass transport in phase boundaries between different ionic materials: Experimental studies and formal considerations

Abstract

Internal and external interfaces in solids exhibit completely different transport properties compared to the bulk. Transport parallel to grain or phase boundaries is usually strongly enhanced. Transport perpendicular to an interface is usually blocked, i.e., transport across an interface is often much slower. Due to the high density of interfaces in modern micro- and nanoscaled devices, a severe influence on the total transport properties can be expected. In contrast to diffusion in metal grain boundaries, transport phenomena in boundaries of ionic materials are still less understood. The specific transport properties along metal grain boundaries are explained by structural factors like packing densities or dislocation densities in the interface region. In most studies dealing with ionic materials, the interfacial transport properties are merely explained by the influence of space charge regions. In this study the influence of the interface structure on the interfacial transport properties of ionic materials is discussed in analogy to metallic materials. A qualitative model based on the density of misfit dislocations and on interfacial strain is introduced for (untilted and untwisted) phase boundaries. For experimental verification, the interfacial ionic conductivity of different multilayer systems consisting of stabilised ZrO₂ and an insulating oxide is investigated as a funtion of structural mismatch. As predicted by the model, the interfacial conductivity increases when the lattice mismatch is increased.

Graphical abstract

Elastic strain at interfaces and its influence on ionic conductivity in nanoscaled solid electrolyte thin films--theoretical considerations and experimental studies

Ionic transport in solids parallel to grain or phase boundaries is usually strongly enhanced compared to the bulk. Transport perpendicular to an interface (across an interface) is often much slower. Therefore in modern micro- and nanoscaled devices, a severe influence on the ionic/atomic transport properties can be expected due to the high density of interfaces.Transport processes in boundaries of ionic materials are still not understood on an atomic scale. In most of the studies on ionic materials the interfacial transport properties are explained by the influence of space charge regions. Here we discuss the influence of interfacial strain at semicoherent or coherent heterophase boundaries on ionic transport along these interfaces in ionic materials. A qualitative model is introduced for (untilted and untwisted) hetero phase boundaries. For experimental verification, the interfacial oxygen ionic conductivity of different multilayer systems consisting of cubic ZrO(2) stabilised by aliovalent dopands (YSZ, CSZ) and an insulating oxide is investigated as a function of structural mismatch. Recent results on extremely fast ionic conduction in YSZ/SrTiO(3) thin film systems ("colossal ionic concuctivity at interfaces") is discussed from the viewpoint of strain effects.

Effect of a single dislocation in a heterostructure layer on the local polarization of a ferroelectric layer

We study, on an atomic scale, the influence of a single dislocation in a SrTiO3 sublayer on the local ferroelectric polarization of the neighboring ferroelectric PbZr0.2Ti0.8O3 (PZT) sublayer in an epitaxial SrTiO3/PbZr0.2Ti0.8O3/SrTiO3 three-layer heterostructure. The strain field of the dislocation in the SrTiO3 layer propagates across the interface into the PZT layer and leads to a strong variation of the c-lattice parameter of the PZT layer. Accompanying a strong reduction of the c-lattice parameter, the off-center displacements of the Zr/Ti atoms away from the center of the oxygen octahedra are also strongly decreased, resulting in a decrease of the local spontaneous polarization by up to 48%.

Vortex polarization states in nanoscale ferroelectric arrays

Two-dimensional arrays of ferroelectric lead zirconate titanate (PZT) nanodots were fabricated using pulsed laser deposition through ultrathin anodic aluminum oxide membrane stencil masks. The static distribution of polarization configurations was investigated using in- and out-of-plane piezoresponse force microscopy (PFM). The observed presence of an in-plane polarization component in nominally (001) oriented PZT suggests the existence of a significant deviation from the regular tetragonal structure that allows the formation of complex core-polarization states. Core-polarization states may indicate the presence of quasi-toroidal polarization ordering. The experimental results are compared with a theoretical model to determine the fingerprint of a vortex polarization state in PFM.

Treatment with azathioprine and cyclic methylprednisolone has little or no effect on bioactivity in anti-interferon beta antibody-positive patients with multiple sclerosis

Background

It is unknown whether immunosuppression of patients who have developed interferon-β (IFN-β) neutralizing antibodies (NAbs) hastens disappearance of NAbs in the blood.

Objective

We wanted to test whether immunosuppression with cyclic methylprednisolone (MP) in combination with azathioprine (AZA) for 6 months accelerates recovery of IFN-β bioactivity in patients with multiple sclerosis (MS) with abolished in-vivo myxovirus resistance protein A (MxA) mRNA response to IFN-β.

Methods

We included 13 patients with MS with NAbs and a low IFN-β bioavailability detected by the MxA-mRNA response in a descriptive, non-randomized trial. Another 14 NAb-positive patients with a low MxA-mRNA response served as controls. The primary outcome was the fraction of patients who regained an MxA-mRNA response to IFN-β. NAbs were measured by means of a clinically validated cytopathic effect assay and a new reporter gene assay. The in-vivo MxA-mRNA response was measured by real-time polymerase chain reaction.

Results

A total of 11 patients in the treatment group completed the trial. In all, two of these 11 patients regained an in-vivo MxA-mRNA response as compared to one of 14 patients in the control group.

Conclusion

Treatment with AZA and cyclic MP for 6 months has little or no effect on IFN-β bioactivity in NAb-positive patients with MS.

Experimental observation of a torus doubling of a metal/ferroelectric film/semiconductor capacitor

A metal-ferroelectric-semiconductor (MFS) structure was used as a nonlinear capacitor in a series resonance circuit. The following materials were used as components of the MFS structure: aluminium as the metal electrode, Bi4Ti3O12 film as the ferroelectric, and p-type silicon as the semiconductor. The system was driven by a single frequency at suitably chosen amplitudes. Besides the sequences of period-doubling bifurcations which were already observed in the series resonance circuit with a pure ferroelectric capacitor, we found regions with torus-doubling bifurcations by varying the frequency of the driving voltage at suitably high amplitudes. Comparing the behaviour of the series resonance circuit with a pure ferroelectric capacitor and with the MFS structure, we attribute the reason for the new effect of torus doubling to the properties of the ferroelectric-semiconductor boundary layer.

Using measurements of neutralizing antibodies: the challenge of IFN-? therapy

Although the occurrence of neutralizing antibodies (NAbs) to interferon (IFN)-beta has been acknowledged since the pivotal trials of IFN-beta in multiple sclerosis (MS), the effect of these antibodies has for several reasons been debated. The main reason for the controversies has been insufficient knowledge of the fact that clinically relevant NAbs do not appear until 12-18 months after initiation of IFN-beta therapy which make studies of 2 years or less unsuited to assess the clinical relevance of NAbs. Further, changes in NAb affinity occur and contribute to increase NAb effects by time. The present paper reviews our current knowledge of NAbs and stresses the importance of using measurements of NAbs routinely. It is concluded that NAb titres are important for the biological response to IFN-beta. Patients with low or intermediate titres may have preserved a full or partial biological response and might still benefit from IFN-beta therapy. However, persistent high titres of NAbs indicate an abrogation of the biological response and, hence, absence of therapeutic efficacy, and this observation should lead to a change of therapy. The application of the existing information about NAbs in clinical practice would lead to improved efficacy of IFN-beta treatment for the benefit of patients with MS.

Coupled ultrafast lattice and polarization dynamics in ferroelectric nanolayers

We report the first analysis of the polarization and lattice dynamics in a metal/ferroelectric/metal nanolayer system by femtosecond x-ray diffraction. Two Bragg reflections provide information on the coupled dynamics of the two relevant phonon modes for ferroelectricity in perovskites, the tetragonal distortion and the soft mode. Optical excitation of the SrRuO(3) metal layers generates giant stress (>1 GPa) compressing the PbZr(0.2)Ti(0.8)O(3) layers by up to 2%. The resulting change of tetragonality reaches a maximum after 1.3 ps. As a result, the ferroelectric polarization P is reduced by up to 100% with a slight delay that is due to the anharmonic coupling of the two modes.

Influence of gas atmosphere and temperature on the conductivity and the photoconductivity of a TiO2single crystal in the surface region

The electrical photoconductivity and conductivity at (and near) the surface of a TiO(2) single crystal (rutile) was studied in a range of temperatures between 300 and 573 K and under different ambient gases (oxygen and nitrogen) by means of impedance spectroscopy. The long times required (many hours) to reach steady state photoconductivity can be explained by the reduction of the material upon illumination. At about 475 K a maximum is observed in the equilibrium photoconductivity and a minimum in the rate constants of the rise and decay after switching on and off, respectively, the light. After switching off the light a fast decay takes place during the first milliseconds followed by a slow exponential decay. The first one is related to recombination through defects, while the latter is due to re-oxidation processes of the material. The results are correlated with measurements of photocatalytic activity.