Magnetic order and competition with superconductivity in (Ho-Er)Ni2B2C.

The rare earth magnetic order in pure and doped Ho(1-x)ErxNi2B2C (x = 0, 0.25, 0.50, 0.75, 1) single crystal samples was investigated using magnetization and neutron diffraction measurements. Superconducting quaternary borocarbides, RNi2B2C where R = Ho, Er , are magnetic intermetallic superconductors with the transition temperatures~10 K in which long range magnetic order develops in the same temperature range and competes with superconductivity. Depending on the rare earth composition the coupling between superconductivity and magnetism creates several phases, ranging from a near reentrant superconductor with a mixture of commensurate and incommensurate antiferromagnetism to an incommensurate antiferromagnetic spin modulation with a weak ferromagnetic component. All of these phases coexist with superconductivity. RKKY magnetic interactions are used to describe the magnetic orders in the pure compounds. However, the doping of Er on Ho sites which have two strong magnetic moments with two different easy directions creates new and complicated magnetic modulations with possible local disorder effects. One fascinating effect is the development of an induced magnetic state resembling the pure and doped R2CuO4 cuprate with R = Nd and Pr.

The relationship between anogenital distance and lifelong premature ejaculation.

BACKGROUND: Many diseases have been associated with anogenital distance, as an indicator of intrauterine androgen exposure. OBJECTIVES: The aim of this study was to investigate the association between lifelong premature ejaculation and anogenital distance. MATERIALS AND METHODS: The study included 140 participants: 70 with lifelong premature ejaculation (group 1) and 70 without any ejaculatory complaints (group 2). Premature Ejaculation Diagnostic Tool and stopwatch intravaginal ejaculatory latency time were recorded from all participants in order to evaluate ejaculatory function. Two variants of anogenital distance were measured: anogenital distance (from anus to the posterior base of the scrotum) from anus to the posterior base of the scrotum and anogenital distance (from anus to the cephalad insertion of the penis) to the cephalad insertion of the penis. We compared differences between groups and correlations between anogenital distance variants and patients' characteristics. RESULTS: The groups were similar in terms of age, BMI, and total testosterone levels. The mean anogenital distance (from anus to the posterior base of the scrotum) scores were 59.45 ± 10.76 vs. 55.02 ± 10.13 (p = 0.01), and anogenital distance (from anus to the cephalad insertion of the penis) scores were 128.37 ± 22.2 vs. 126.78 ± 16.21 (p = 0.63) in groups 1 and 2, respectively. Significant correlation was observed between anogenital distance (from anus to the posterior base of the scrotum) and Premature Ejaculation Diagnostic Tool scores (r = 0.199, p = 0.019) and intravaginal ejaculatory latency time (r = -0.185, p = 0.028). There were no statistically significant differences between anogenital distance (from anus to the posterior base of the scrotum) scores and total testosterone levels and between anogenital distance (from anus to the cephalad insertion of the penis) and Premature Ejaculation Diagnostic Tool scores or intravaginal ejaculatory latency time. CONCLUSIONS: These results suggest that longer anogenital distance is associated with higher possibility of lifelong premature ejaculation. However, further studies are needed to confirm our results.

Pain intensity and its objective determinants following implant surgery and sinus lifting: A 1-year prospective study.

OBJECTIVES: The main goal of this study was to evaluate the relationship between postoperative pain and short-term implant survival. Objective parameters, such as implant-related factors (type, diameter, length) and the surgical approach were also assessed to correlate them with pain. MATERIALS AND METHODS: This prospective, single-center study consisted of 144 patients scheduled for the surgical placement of one or more implants either with conventional surgery or with sinus-lifting together. All patients were asked to complete a questionnaire form of pain with a visual-analog scale (VAS, 1-10) for 7 days following surgery. The association of pain scores at each time-point was assessed on implant- and surgery-related factors. RESULTS: The overall cumulative survival rate of 546 implants in 144 patients was 98.17 % (10 implants lost) after 1-year follow-up. No statistical difference was found in pain (VAS) scores between patients with loss and survived implants at any observation period. The length and diameter of placed implants and the presence of a sinus-lifting procedure did not influence the pain scores at any period (P > 0.05). In patients with bilateral sinus lifting, the decrease in pain scores was significant after 3 days (P < 0.05), whereas it was significant after 6 hours for the conventionally treated group (P < 0.01). Although no severe pain was reported at any time, this study found a significant difference in pain intensities among different implant brands. CONCLUSIONS: This study was able to show that increased postoperative pain is not a sign of early implant failure. In addition to this, the implant dimensions and presence of sinus lifting procedure did not influence the pain experience. However, the bilateral sinus lifting prolongs the recovery time.

Cartilage tissue engineering on macroporous scaffolds using human tooth germ stem cells.

The main objective was to study cartilage regeneration through differentiation of human tooth germ stem cells (HTGSCs) into chondrocytes on different three-dimensional (3D) scaffolds (PCL, PLLA and PCL-PLLA). Scaffold topographies were studied by scanning electron microscopy and it was found that the scaffolds had interconnected macroporous structures. HTGSCs were isolated from impacted third molar tooth germs of young adult patients and grown for 3 weeks on the scaffolds in chondrogenic differentiation medium. Cell proliferation on the scaffolds was determined by MTS assay and it was observed that all scaffolds supported cell proliferation. Immunostaining was carried out for morphological and differentiation analyses. Immunohistochemical analyses revealed that the cells attached onto the scaffolds and deposited cartilage-specific extracellular matrix (ECM). Real-time PCR was performed to determine the expression levels of cartilage-specific genes. After 21 days of incubation in cartilage differentiation medium, expression of collagen type II increased only in the cells seeded onto PCL-PLLA blend scaffolds. Similarly, aggrecan expression was the highest on PCL-PLLA scaffolds after 3 weeks. These results suggest that all the scaffolds, and especially PCL-PLLA, were suitable for chondrogenic differentiation of HTGSCs. Copyright © 2015 John Wiley & Sons, Ltd.

Charge order and its connection with Fermi-liquid charge transport in a pristine high-T(c) cuprate.

Electronic inhomogeneity appears to be an inherent characteristic of the enigmatic cuprate superconductors. Here we report the observation of charge-density-wave correlations in the model cuprate superconductor HgBa2CuO(4+δ) (T(c)=72 K) via bulk Cu L3-edge-resonant X-ray scattering. At the measured hole-doping level, both the short-range charge modulations and Fermi-liquid transport appear below the same temperature of about 200 K. Our result points to a unifying picture in which these two phenomena are preceded at the higher pseudogap temperature by q=0 magnetic order and the build-up of significant dynamic antiferromagnetic correlations. The magnitude of the charge modulation wave vector is consistent with the size of the electron pocket implied by quantum oscillation and Hall effect measurements for HgBa2CuO(4+δ) and with corresponding results for YBa2Cu3O(6+δ), which indicates that charge-density-wave correlations are universally responsible for the low-temperature quantum oscillation phenomenon.

Local weak ferromagnetism in single-crystalline ferroelectric BiFeO3.

Polarized small-angle neutron scattering studies of single-crystalline multiferroic BiFeO(3) reveal a long-wavelength spin density wave generated by ∼1° spin canting of the spins out of the rotation plane of the antiferromagnetic cycloidal order. This signifies weak ferromagnetism within mesoscopic regions of dimension 0.03 microns along [110], to several microns along [111], confirming a long-standing theoretical prediction. The average local magnetization is 0.06 µ(B)/Fe. Our results provide an indication of the intrinsic macroscopic magnetization to be expected in ferroelectric BiFeO(3) thin films under strain, where the magnetic cycloid is suppressed.

Smectic-A and smectic-C phases and phase transitions in 8S5 liquid-crystal-aerosil gels.

High-resolution x-ray scattering studies of the nonpolar thermotropic liquid crystal 4-n-pentylphenylthiol-4'-n-octyloxybenzoate (8S5) in aerosil gel nanonetworks reveal that the aerosil-induced disorder significantly alters both the nematic to smectic-A and smectic-A to smectic-C phase transitions. The limiting 8S5 smectic-A correlation length follows a power-law dependence on the aerosil density in quantitative agreement with the limiting lengths measured previously in other smectic-A liquid crystal gels. The smectic-A to smectic-C liquid crystalline phase transition is altered fundamentally by the presence of the aerosil gel. The onset of the smectic-C phase remains relatively sharp but there is an extended coexistence region where smectic-A and smectic-C domains can exist.

Giant effect of uniaxial pressure on magnetic domain populations in multiferroic bismuth ferrite.

Neutron diffraction is used to show that small (∼7 MPa, or 70 bar) uniaxial pressure produces significant changes in the populations of magnetic domains in a single crystal of 2% Nd-doped bismuth ferrite. The magnetic easy plane of the domains converted by the pressure is rotated 60° relative to its original position. These results demonstrate extreme sensitivity of the magnetic properties of multiferroic bismuth ferrite to tiny (less than 10(-4)) elastic strain, as well as weakness of the forces pinning the domain walls between the cycloidal magnetic domains in this material.

The effect of Si nano-columns in 2-D and 3-D on cellular behaviour: nanotopography-induced CaP deposition from differentiating mesenchymal stem cells.

Si nano-columns were deposited in 2-D and 3-D in the form of well-defined geometries by physical vapor deposition. The films were grown by e-beam evaporation with an angle between source and substrate. The Si nano-columns were deposited in the shape of spiral with two different incoming atomic flux angle so that the manipulation of nano-columns in 3-D (out-of-plane) was obtained. The Si nano-columns were also grown as vertical stick with square, triangle and linear cross sections in 2D (in-plane). Rat bone marrow mesenchymal stem cells (MSCs) were cultured on these different Si nanosurfaces. MTS assay was carried out to determine the cell proliferation and viability based on different nanotopographies. For the evaluation of cell distribution and morphology, a SEM (Scanning Electron Microscopy) analysis was performed. Any CaP deposition on Si nanosurfaces was observed using energy dispersive X-Ray spectroscopy in SEM (SEM-EDX). After 4 days of culture, there was a higher value of cell proliferation on square columns and spiral Si nano-columns grown with 85 degrees of incoming atomic flux. The cell attachment and spreading was also affected by the geometry of Si nano-columns. While there were still cells showing round/spherical morphology with minimal spreading on conventional Si surfaces, most of the cells cultured on different Si nanotopographies attached on the surface and displayed flattened morphology, especially on the square columns surface. Moreover, CaP deposition was discovered on square columns and spiral films with 85 degrees substrate angle. So, it can be concluded that there is a clear correlation between cell responses and nano-sized geometry on Si surface and it is possible to induce cellular differentiation and CaP formation in certain geometrical constraints.

Isolation and characterization of stem cells derived from human third molar tooth germs of young adults: implications in neo-vascularization, osteo-, adipo- and neurogenesis.

A number of studies have reported in the last decade that human tooth germs contain multipotent cells that give rise to dental and peri-odontal structures. The dental pulp, third molars in particular, have been shown to be a significant stem cell source. In this study, we isolated and characterized human tooth germ stem cells (hTGSCs) from third molars and assessed the expression of developmentally important transcription factors, such as oct4, sox2, klf4, nanog and c-myc, to determine their pluri-potency. Flow-cytometry analysis revealed that hTGSCs were positive for CD73, CD90, CD105 and CD166, but negative for CD34, CD45 and CD133, suggesting that these cells are mesenchymal-like stem cells. Under specific culture conditions, hTGSCs differentiated into osteogenic, adipogenic and neurogenic cells, as well as formed tube-like structures in Matrigel assay. hTGSCs showed significant levels of expression of sox2 and c-myc messenger RNA (mRNA), and a very high level of expression of klf4 mRNA when compared with human embryonic stem cells. This study reports for the first time that hTGSCs express developmentally important transcription factors that could render hTGSCs an attractive candidate for future somatic cell re-programming studies to differentiate germs into various tissue types, such as neurons and vascular structures. In addition, these multipotential hTGSCs could be important stem cell sources for autologous transplantation.

Spin waves and quantum criticality in the frustrated XY pyrochlore antiferromagnet Er2Ti2O7.

We report detailed measurements of the low temperature magnetic phase diagram of Er2Ti2O7. Heat capacity and time-of-flight neutron scattering studies of single crystals reveal unconventional low-energy states. Er3+ magnetic ions reside on a pyrochlore lattice in Er2Ti2O7, where local XY anisotropy and antiferromagnetic interactions give rise to a unique frustrated system. In zero field, the ground state exhibits coexisting short and long-range order, accompanied by soft collective spin excitations previously believed to be absent. The application of finite magnetic fields tunes the ground state continuously through a landscape of noncollinear phases, divided by a zero temperature phase transition at micro{0}H{c} approximately 1.5 T. The characteristic energy scale for spin fluctuations is seen to vanish at the critical point, as expected for a second order quantum phase transition driven by quantum fluctuations.

High-resolution x-ray study of nematic-smectic-A and smectic-A-reentrant-nematic transitions in liquid-crystal-aerosil gels.

We have studied the effects of quenched random disorder created by dispersed aerosil nanoparticle gels on the nematic to smectic- A (N- SmA ) and smectic- A to reentrant nematic ( SmA -RN) phase transitions of thermotropic liquid-crystal mixtures of hexyloxycyanobiphenyl (6OCB) and octyloxycyanobiphenyl (8OCB). These effects are probed using high-resolution synchrotron x-ray diffraction techniques. We find that the reentrant characteristics of the system are largely unchanged by the presence of the aerosil gel network. By comparing measurements of the smectic static structure amplitude for this 8OCB- 6OCB+aerosil system with those for butyloxybenzilidene-octylaniline (4O.8)+aerosil gels, we find that the short-range smectic order in the smectic- A phase is significantly weaker in the reentrant system. This result is consistent with the behavior seen in pure 8OCB-6OCB mixtures. The strength of the smectic ordering decreases progressively as the 6OCB concentration is increased. Detailed line shape analysis shows that the high- and low-temperature nematic phases (N and RN) are similar to each other.

High-resolution x-ray scattering study of the effect of quenched random disorder on the nematic-smectic-A transition.

Using high-resolution x-ray scattering, the effect of quenched random disorder (QRD) on the second-order nematic-smectic-A (N-SmA) phase transition in butyloxybenzilidene-octylaniline (4O.8) has been studied. 4O.8 is a nonpolar liquid crystal (LC) with a monomeric smectic-A phase. The QRD is created by aerosil nanoparticles which gelate to form a three-dimensional network, confining the LC. The QRD caused by the aerosil gel generates quenched random fields acting on both the nematic and smectic-A order parameters. This results in the destruction of the quasi-long-range order of the smectic-A phase. The x-ray scattering data are modeled with a structure factor composed of two terms, one thermal and one static, corresponding to the connected and disconnected susceptibilities, respectively. Unlike previous studies, the two parts of the structure factor are decoupled by allowing different thermal and static correlation lengths. Our fitting procedure involves temperature-dependent and temperature-independent (global) variables. The amplitude and the parallel correlation length for the thermal part of the line-shape show critical-like behavior both above and below the transition temperature. Detailed analysis reveals that the thermal correlation length does not truly diverge at the phase transition. This effect is discussed on the basis of a cutoff for the divergence caused by the random fields generated by the aerosil network confining the liquid crystal. The intensity of the static term in the line-shape behaves like the order parameter squared at a conventional second-order phase transition. The effective order parameter critical exponent shows an evolution with increasing aerosil gel density ranging from the Gaussian tricritical value to the 3D- XY value. The results of a pseudocritical scaling analysis are compared to an analysis of 4O.8+aerosil heat capacity data and discussed using a phenomenological correlation between the nematic range of pure liquid crystals and the aerosil mass density, rho{s}.

Effects of disorder on a smectic--nematic phase transition.

Using x-ray scattering, we have studied the nematic to smectic- phase transition of the liquid crystal butyloxybenzilidene-octylaniline confined in an aerosil network. We find that the disorder introduced by the aerosil network destroys the long-range nature of the phase transition, and that the transition becomes similar to that observed in a finite-size system, with finite low-temperature correlation lengths of the ordered moments and a power-law behavior of the order parameter with respect to the reduced temperature observable in a limited temperature range. We also show evidence for a systematic evolution of the effective order parameter critical exponent beta with increasing disorder.

First-order isotropic-smectic-A transition in liquid-crystal-aerosil gels.

The short-range order which remains when the isotropic to smectic- A transition is perturbed by a gel of silica nanoparticles (aerosils) has been studied using high-resolution synchrotron x-ray diffraction. The gels have been created in situ in decylcyanobiphenyl, which has a strongly first-order isotropic to smectic- A transition. The effects are determined by detailed analysis of the temperature and gel density dependence of the smectic structure factor. In previous studies of the continuous nematic to smectic- A transition in a variety of thermotropic liquid crystals the aerosil gel appeared to pin, at random, the phase of the smectic density modulation. For the isotropic to smectic- A transition the same gel perturbation yields different results. The smectic correlation length decreases more slowly with increasing random-field variance in good quantitative agreement with the effect of a random pinning field at a transition from a uniform phase directly to a phase with one-dimensional translational order. We thus compare the influence of random fields on a freezing transition with and without an intervening orientationally ordered phase.