Polar phonons in some compressively stressed epitaxial and polycrystalline SrTiO3 thin films

Several SrTiO3 (STO) thin films without electrodes processed by pulsed laser deposition, of thicknesses down to 40 nm, were studied using infrared transmission and reflection spectroscopy. The complex dielectric responses of polar phonon modes, particularly ferroelectric soft mode, in the films were determined quantitatively. The compressed epitaxial STO films on (100) La0.18Sr0.82Al0.59-Ta0.41O3 substrates (strain 0.9%) show strongly stiffened phonon responses, whereas the soft mode in polycrystalline film on (0001) sapphire substrate shows a strong broadening due to grain boundaries and/or other inhomogeneities and defects. The stiffened soft mode is responsible for a much lower static permittivity in the plane of the compressed film than in the bulk samples.Comment: 11 page

Polarization relaxation in thin-film relaxors compared to that in ferroelectrics

Epitaxial thin films of relaxor PbMg1/3Nb2/3O3 and PbSc0.5Nb0.5O3, and ferroelectric PbZr0.65Ti0.35O3, Pb0.955La0.045Zr0.65Ti0.35O3, and Ba0.4Sr0.6TiO3 were prepared, and their dielectric properties were studied in a broad range of the measurement conditions. In the ferroelectric state, the presence and the change of configuration of the domains determined both the dynamic dielectric nonlinearity and the polarization hysteresis. In thin-film relaxors, the orientation of the randomly interacting dipoles in a random field was responsible for the dynamic dielectric nonlinearity, while the observed hysteresis was suggested to arise due to connection between the applied field and the relaxation times of both the dipoles and the internal field. In thin-film (Ba,Sr)TiO3, the high-temperature dielectric hysteresis was found to be relaxorlike.Comment: 20 pages, 10 figures, submitted to Phys. Rev. B 17.03.200

The (cost-)effectiveness of a lifestyle physical activity intervention in addition to a work style intervention on the recovery from neck and upper limb symptoms in computer workers

BACKGROUND: Neck and upper limb symptoms are frequently reported by computer workers. Work style interventions are most commonly used to reduce work-related neck and upper limb symptoms but lifestyle physical activity interventions are becoming more popular to enhance workers health and reduce work-related symptoms. A combined approach targeting work style and lifestyle physical activity seems promising, but little is known on the effectiveness of such combined interventions. METHODS/DESIGN: The RSI@Work study is a randomised controlled trial that aims to assess the added value of a lifestyle physical activity intervention in addition to a work style intervention to reduce neck and upper limb symptoms in computer workers. Computer workers from seven Dutch companies with frequent or long-term neck and upper limb symptoms in the preceding six months and/or the last two weeks are randomised into three groups: (1) work style group, (2) work style and physical activity group, or (3) control group. The work style intervention consists of six group meetings in a six month period that take place at the workplace, during work time, and under the supervision of a specially trained counsellor. The goal of this intervention is to stimulate workplace adjustment and to improve body posture, the number and quality of breaks and coping behaviour with regard to high work demands. In the combined (work style and physical activity) intervention the additional goal is to increase moderate to heavy physical activity. The control group receives usual care. Primary outcome measures are degree of recovery, pain intensity, disability, number of days with neck and upper limb symptoms, and number of months without neck and upper limb symptoms. Outcome measures will be assessed at baseline and six and 12 months after randomisation. Cost-effectiveness of the group meetings will be assessed using an employer's perspective. DISCUSSION: This study will be one of the first to assess the added value of a lifestyle physical activity intervention in addition to a work style intervention in reducing neck and upper limb symptoms of computer workers. The results of the study are expected in 2007

A randomized, placebo-controlled double-blinded comparative clinical study of five over-the-counter non-pharmacological topical analgesics for myofascial pain: single session findings

<p>Abstract</p> <p>Objectives</p> <p>To investigate the effects of topical agents for the treatment of Myofascial Pain Syndrome (MPS) and Myofascial Trigger Point (MTRP).</p> <p>Methods</p> <p>Subjects with an identifiable trigger point in the trapezius muscle, age 18-80 were recruited for a single-session randomized, placebo-blinded clinical study. Baseline measurements of trapezius muscle pressure pain threshold (PPT: by pressure algometer) along with right and left cervical lateral flexion (rangiometer) were obtained by a blinded examiner. An assessor blinded to the outcomes assessments applied one of 6 topical formulations which had been placed in identical plastic containers. Five of these topicals were proposed active formulations; the control group was given a non-active formulation (PLA). Five minutes after the application of the formula the outcome measures were re-tested. Data were analyzed with a 5-way ANOVA and Holms-adjusted t-tests with an alpha level of 0.05.</p> <p>Results</p> <p>120 subjects were entered into the study (63 females; ages 16-82); 20 subjects randomly allocated into each group. The pre- and post-treatment results for pressure threshold did show significant intra-group increases for the Ben-Gay Ultra Strength Muscle Pain Ointment (BG), the Professional Therapy MuscleCare Roll-on (PTMC roll-on) and Motion Medicine Cream (MM) with an increased threshold of 0.5 kg/cm²(+/-0.15), 0.72 kg/cm^{<b>2 </b>}(+/-0.17) and 0.47 Kg/cm^{<b>2 </b>}(+/-0.19) respectively. With respect to the inter-group comparisons, PTMC roll-on showed significant increases in pressure threshold compared with Placebo (PLA) (p = 0.002) and Icy Hot Extra Strength Cream (IH) (p = 0.006). In addition, BG demonstrated significant increases in pressure threshold compared with PLA (p = 0.0003).</p> <p>Conclusions</p> <p>With regards to pressure threshold, PTMC roll-on, BG and MM showed significant increases in pain threshold tolerance after a short-term application on a trigger points located in the trapezius muscle. PTMC roll-on and BG were both shown to be superior vs placebo while PTMC was also shown to be superior to IH in patients with trigger points located in the trapezius muscle on a single application.</p> <p>CMCC Research Ethics Board Approval # 1012X01, 2011</p

High-Tc Superconducting YBa2Cu3O7-δ Films and YBa2Cu3O7-δ/PrBa2Cu3O7-δ Superlattices Deposited by Laser Ablation

High Tc superconducting YBa2Cu3O7-d thin films and YBa2Cu37-δ/PrBa2Cu3O7-δ superlattices with various periods and layer thicknesses were deposited by laser ablation on SrTiO3 (100) single crystal substrates using an XeCl excimer laser (λ = 308 nm). The structure of the films was studied by SEM/EDS and X-ray diffraction. The films and superlattices deposited in an in situ process were epitaxial with the c-axis perpendicular to the substrate surface and the a- and b-axes parallel with the SrTiO3 [100] or [010] directions. The electrical properties were studied by measuring the current-voltage characteristics, resistivity and critical current. For the in situ deposited YBa2Cu3O7-d films the zero resistivity temperature was 87 to 90 K and the critical current at 77 K was above 2 × 106 A/cm2. For the films deposited at room temperature and post annealed under in situ deposition conditions, the critical temperature was the same, but the critical current was 0.5 × 106 A/cm2

Diamond synthesis at high filament temperature

Diamond particles and films have been deposited on silicon wafer by using hot filament assisted chemical vapour deposition (HFCVD). Tantalum carbide filaments were used in the temperature range of 2700-2890°C. The filament can be repeatedly used for diamond deposition in CH4/H2/O2 atmosphere without deformation in its geometry. Diamond structure was deposited at high methane concentration up to 12% at filament temperature of 2890°C. By introducing 5.6% of oxygen, the methane concentration can be extended to 16%. Diamond particles and films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy

Diamond Deposition Using a Grid Filament

A grid tantalum filament of a dimension of 3 x 4 cm2 was used for diamond synthesis by hotfilament assisted chemical vapour deposition (HFCVD). After proper carburization, the filament could be used for multi-cycles of deposition. By heating the filament to 2400°C in 8% CH4 mixed with H2, diamond has been deposited at rate of about 5 µm/hour on (100) oriented silicon substrate placed 5 mm away from the filament. By X-ray diffraction (XRD), the structure of the films deposited in the mixture of CH4 and H2 was characterized as diamond, while tantalum oxide was found in the presence of oxygen during deposition. The deposited diamond appeared uniform over an area of 2 x 3 cm2 observed by scanning electron microscopy (SEM) perhaps due to the stable filament geometry. Raman spectra of these films showed a sharp peak near 1332 cm-l, which indicated the presence of a large amount of sp3 bonds in the film. The present grid filament can be scaled-up for large area diamond deposition

Low-temperature relaxor state induced by epitaxial compression in PbSc0.5Nb0.5O3 films

International audienceThe use of high-performance perovskite-structure epitaxial relaxor ferroelectric films [S. H. Baek et al., Science 334, 958 (2011)] is hindered by the lack of knowledge of epitaxial effects therein. It is experimentally shown here that a biaxial epitaxial compression can favor the relaxor state over ferroelectricity. The absence of the ferroelectric transition and the existence of the low-temperature relaxor state are evidenced by a combination of x-ray diffraction, dielectric, polarization, and optical studies of PbSc0.5Nb0.5O3 films epitaxially grown on La0.5Sr0.5CoO3/MgO(001). This finding is beyond existing models of polarization in perovskite-structure epitaxial films and beyond the established ability to induce ferroelectricity by an epitaxial strain