2,4,6-Triphenylphosphinine and 2,4,6-triphenylposphabarrelene revisited: synthesis, reactivity and coordination chemistry

Important aspects of the synthesis, reactivity and coordination chemistry of 2,4,6-triphenylphosphinine and 2,4,6-triphenylphosphabarrelene have been revisited.

High-average-power, 50-fs parametric amplifier front-end at 1.55 μm

An average-power-scalable, two-stage optical parametric chirped pulse amplifier is presented providing 90-μJ signal pulses at 1.55 μm and 45-μJ idler pulses at 3.1 μm at a repetition rate of 100 kHz. The signal pulses were recompressible to within a few percent of their ~50-fs Fourier limit in anti-reflection coated fused silica at negligible losses. The overall energy conversion efficiency from the 1030-nm pump to the recompressed signal reached 19%, significantly reducing the cost per watt of pump power compared to similar systems. The two-stage source will serve as the front-end of a three-stage system permitting the development of novel experimental strategies towards laser-based imaging of molecular structures and chemical reactivity.

Rehabilitation in Patients With Coronary Heart Disease: Participation and Its Effect on Prognosis

BACKGROUND

In Germany, rehabilitation is considered to be indicated after an acute hospital stay for the treatment of a severe cardiac condition. In comparative studies, at least 51% of German hospital patients with coronary heart disease (CHD) who were entitled to rehabilitative measures actually took part n rehabilitation.

METHODS

We examined data on 1910 patients with CHD who took part in two prospective cohort studies at the University Hospital of Halle (Saale) in the years 2007-2011. We contacted these patients again with a questionnaire to determine which ones had undergone rehabilitation. For patients who died before we could contact them, the attempt was made to obtain the dates and causes of death from the local authorities. The primary endpoint of was overall mortality.

RESULTS

The median duration of follow-up was 136 ± 71 weeks. 727 patients (38.1%) had applied for rehabilitation during their acute hospitalization, but only 552 patients (28.9%) actually underwent it. Patients who did not undergo rehabilitation were older than those who did (68.6 ± 10.3 vs. 64.9 ± 10.5 years) and suffered more commonly from diabetes (41.3% vs. 33.7%; p = 0.002), arterial hypertension (89.2% vs. 85.3%; p = 0.017), and peripheral arterial occlusive disease (15.3% vs. 9.8%; p = 0.002). There were more smokers in the rehabilitation group. Kaplan-Meier analysis and multivariate Cox regression analysis both showed that the patients who underwent rehabilitation had lower mortality (hazard ratio 0.067, 95% confidence interval 0.025-0.180, p < 0.001).

CONCLUSION

Rehabilitation for cardiac patients was associated with lower mortality. Fewer patients underwent rehabilitation in this study than in other, comparable studies. Those who did not were older and had a greater burden of accompanying disease.

Feasibility and safety of rehabilitation after venous thromboembolism

BACKGROUND

Venous thromboembolism is a life-threatening disease. In survivors, different degrees of functional complaints need to be restored or prevented (eg, post-thrombotic syndrome, pulmonary hypertension). Therefore, rehabilitation after venous thromboembolism is recommended in Germany. However, a structured rehabilitation program has not been defined for this indication. Here, we present the experience of a single rehabilitation center.

METHODS

Data from consecutive pulmonary embolism (PE) patients who were referred for a 3-week inpatient rehabilitation program from 2006 to 2014 were retrospectively evaluated.

RESULTS

In all, 422 patients were identified. The mean age was 63.9±13.5 years, the mean body mass index (BMI) was 30.6±6.2 kg/m2, and 51.9% were female. Deep vein thrombosis according to PE was known for 55.5% of all patients. We applied a wide range of therapeutic interventions such as bicycle training with monitored heart rate in 86.7%, respiratory training in 82.5%, aquatic therapy/swimming in 40.1%, and medical training therapy in 14.9% of all patients. Adverse events (AEs) occurred in 57 patients during the 3-week rehabilitation period. The most common AEs were cold (n=6), diarrhea (n=5), and infection of the upper or lower respiratory tract that was treated with antibiotics (n=5). However, three patients under anticoagulation therapy suffered from bleeding, which was clinically relevant in one. Four patients (0.9%) had to be transferred to a primary care hospital for non-PE-associated reasons (acute coronary syndrome, pharyngeal abscess, and acute abdominal problems). No influence of any of the physical activity interventions on the incidence of any AE was found.

CONCLUSION

Since PE is a life-threatening disease, it seems reasonable to recommend rehabilitation at least in PE patients with an intermediate or high risk. It is shown for the first time in this study that a standard rehabilitation program after PE is safe. However, efficacy and safety in the long term need to be studied prospectively.

Men and women differ in their diurnal expression of monocyte peroxisome proliferator-activated receptor-α in the fed but not in the fasted state

Peroxisome proliferator-activated receptor-α (PPARα) plays a pivotal role in regulating metabolic response to fasting and is an inhibitor of inflammatory pathways in immune cells. It represents a therapeutic target for treatment of several diseases, mainly hyperlipidemia. To shed light on PPARα expression changes in response to fasting, young healthy male and female volunteers were fed or fasted for 24 hours. Monocytes were analyzed every 2 hours to compile both profiles of mRNA and protein expression of PPARα and its interactive partner, the circadian pacemaker brain and muscle aryl hydrocarbon receptor nuclear translocator like-1 (BMAL1). We found that women change their diurnal expression profiles of PPARα and BMAL1 when switching from the fed to the fasted state, whereas men do not. Interestingly, the PPARα and BMAL1 profiles of men and women in the fed state are different, whereas the profiles in the fasted state are virtually identical. The finding of diametrically opposite responses of male and female PPARα expression in the fed state might have practical implication in human medicine as PPARα activators like fibrates are used for the therapy of chronic lymphocytic leukemia, microvascular complications in diabetes, and kidney diseases.

Spectral fringes in non-phase-matched SHG and refinement of dispersion relations in the VUV

We consider second harmonic generation (SHG) of ultrashort pulses in the case of strong phase- and group-velocity mismatch. Spectral fringes appear in the second harmonic related to two delayed replicas of the fundamental pulse in the time domain. The fringe separation can be used to evaluate the group-velocity and refractive index of nonlinear crystals at extreme wavelengths. Experimental results with femtosecond pulses in SrB(4)O(7) (SBO) are used to refine the Sellmeier equation describing the n(c) refractive index down to 160 nm, essential for the use of this unique nonlinear crystal for random quasi-phase-matching in the VUV.

Evaluation of the prognostic role of tumor cell podoplanin expression in locally advanced squamous cell carcinoma of the head and neck

BACKGROUND AND PURPOSE

To investigate the potential prognostic role of tumor cell podoplanin expression in patients treated with resection followed by irradiation or chemoradiotherapy for locally advanced squamous cell carcinoma of the head and neck (SCCHN).

MATERIALS AND METHODS

Podoplanin expression (≤10 % versus > 10 %) and 12 other factors were evaluated in 160 patients for their association with locoregional control (LRC), metastases-free (MFS) and overall survival (OS). Other factors were age, gender, Eastern Cooperative Oncology Group (ECOG) performance status, preradiotherapy (pre-RT) hemoglobin level, tumor site, histological grading, T category, N category, American Joint Committee on Cancer (AJCC) stage, human papillomavirus (HPV) status, extent of resection and concurrent chemotherapy.

RESULTS

In multivariate analysis, ECOG performance status 0-1 (risk ratio, RR: 3.01; 95 % confidence interval, CI: 1.42-7.14; p = 0.003), pre-RT hemoglobin levels ≥ 7.45 mmol/l (12 g/dl; RR: 2.03; 95 % CI: 1.04-3.94; p = 0.038), oropharyngeal cancer (RR: 1.25; 95 % CI: 1.01-1.55; p = 0.038) and T category T1-2 (RR: 1.81; 95 % CI: 1.24-2.79; p = 0.002) were significantly associated with improved LRC. T category T1-2 (RR: 1.90; 95 % CI: 1.25-3.06; p = 0.002) and N category N0-2a (RR: 5.22; 95 % CI: 1.96-18.09; p < 0.001) were significantly associated with better MFS. Pre-RT hemoglobin levels ≥ 7.45 mmol/l (RR: 2.44; 95 % CI: 1.27-4.74; p = 0.007), T category T1-2 (RR: 1.97; 95 % CI: 1.36-3.04; p < 0.001) and N category N0-2a (RR: 2.87; 95 % CI: 1.37-6.61; p = 0.005) were significantly associated with improved OS. Podoplanin expression ≤ 10 % showed a trend towards improved OS on both univariate (p = 0.050) and multivariate analysis (RR: 1.86; 95 % CI: 0.96-3.59; p = 0.07).

CONCLUSION

Treatment outcomes were significantly associated with performance status, pre-RT hemoglobin level, tumor site and tumor stage. Tumor cell expression of podoplanin ≤ 10 % showed a trend towards improved OS when compared to podoplanin expression of > 10 %.

NMR Study of Molecular Dynamics in a D ho Columnar Mesophase

In this paper we report the first molecular dynamics study combining fast field-cycling and conven-tional NMR techniques in a thermotropic liquid crystal of discotic molecules exhibiting an ordered columnar hexagonal mesophase. Using the association of these techniques we obtained proton T1 data over a very large domain of Larmor frequencies (ω/2π from 500 Hz to 85 MHz). The proton spin-lattice relaxation results were analysed considering the structure of the mesophase and the types of movements which are expected to influence significantly the relaxation rate, namely local molecu-lar rotational reorientations, inter-columnar self-diffusion and collective movements corresponding to bending and compression of the columns. We verified that these mechanisms dominate the relaxation respectively for high, medium and low Larmor frequencies.

Dynamic Nuclear Polarization Experiments on 19F in Solutions and their Interpretation by the “Pulse Model” of Molecular Collisions

The dynamic fluorine polarization by the Overhauser effect has been studied at four different magnetic field values and at various temperatures in several fluorocarbon solutions. The importance of intermolecular contact couplings is very sensitively dependent on the chemical environment of the fluorine nuclei. The experimental data are interpreted in terms of the stochastic “pulse model” of molecular collisions derived in a preceding paper. The parameters of the model, such as the relative contribution of scalar couplings, the shape and the time scale of collision pulses and the correlation times of the molecular motion are given explicitly for six fluorocarbon solutions of free radicals.

Kernresonanzuntersuchung der Molekülrotation und Selbstdiffusion in festem Benzol: T1ϱ-Spektroskopie/ Nuclear Magnetic Resonance Investigation of Molecular Rotation and Diffusion in Solid Benzene: T1ϱ-Spectroscopy

We have extended previous NMR investigations of the molecular motion in solid benzene to lower proton spin Larmor frequencies using the rotating frame (T1ϱ) technique. The new data show two relaxation mechanisms, namely the well-known rotation of the benzene rings around their sixfold axis and, additionally, the self-diffusion by vacancies. The rotation and diffusion was analyzed by computer optimization of the relaxation models of Haeberlen and Torrey, respectively. The parameters of rotation are essentially consistent with results derived recently from high-frequency T1 measurements. The diffusion parameters are in agreement with preliminary low-frequency T1 measurements, but reveal a dramatic discrepancy by nearly 4 orders of magnitude with respect to tracer experiments of Fox and Sherwood. This behaviour is discussed in terms of correlation effects similar to those observed in plastic and liquid crystals.

Kernresonanzuntersuchung der Molekülrotation in festem Benzol: T1-Spektroskopie / Nuclear Magnetic Resonance Investigation of Molecular Rotation in Solid Benzene: T1-spectroscopy

We have extended Haeberlen’s and Maier’s NMR investigation of the molecular rotation in solid polycrystalline benzene (C6H6), performed in 1967 in the Larmor frequency range from 88 MHz to 22 MHz, to lower frequencies down to 4.4 MHz. In some cases monocrystalline samples were also studied. The extensive data show that the presently accepted model of purely uncorrected rotations of the benzene molecules around their sixfold axis has to be rejected. Instead, two results found, namely

- a slight increase of the rotational activation energy when approaching the melting point of benzene and

- the width of the T1 relaxation minima as a function of the reciprocal temperature suggest an additional relevance of correlated molecular motions, like e.g. the ‘gear-wheel mechanism’ first proposed by Cox. By appropriate modifications of Haeberlen’s theory, i.e. by assuming a rate equation with temperature dependent activation energy and by emphasizing the effect of simultaneous rotations of neighbouring rings compared with the purely statistical, uncorrelated case, we succeeded to describe the considered T1 measurements quantitatively.

Kernmagnetische Messungen von Selbstdiffusions-Koeffizienten in Wasser und Benzol bis zum kritischen Punkt

The most commonly used nuclear magnetic resonance spin-echo methods for determining selfdiffusion coefficients D are described; some experimental data are presented for protons in water and in benzene from room temperature up to the critical point. The results are interpreted in terms of the free-volume rate theory of MACEDO and LITOVITZ. The D-value of benzene may be described by a single activation energy. Water, however, shows such behavior only at high temperatures, thus demonstrating the strong influence of hydrogen bonding. The STOKES-EINSTEIN relation between diffusion coefficient and viscosity is well satisfied over that part of the temperature range where viscosity values are available.

NMR Investigation of Order Fluctuations, Self-Diffusion and Rotational Motions in the Nematic Liquid Crystal MBBA by T1-Relaxation Spectroscopy

We report on measurements of the proton spin T1 relaxation dispersion at various temperatures in the nematic phase of the liquid crystal MBBA in the Larmor frequency range from 2 kHz to 270 MHz, which exceeds previous studies by more than 3 orders of magnitude. The new results cannot be interpreted in terms of either order fluctuations or self-diffusion as recently proposed by Doane et al.1 and Blinc et al.2, respectively. Instead, the dispersion and its temperature dependence indicate the significance of at least three relaxation mechanisms, namely order fluctuations (OF), self-diffusion (SD) and rotation of the molecular ellipsoids about the short axis (R). The combined OF-SD-R model presented in this work allows a quantitative analysis of the experimental findings! The correlation times and activation energies of the three molecular reorientations evaluated from the T1 dispersion by means of a computer optimization procedure are in essential agreement with data provided by other spectroscopic methods [light scattering, tracer technique, dielectric relaxation], but differ from former NMR conclusions.

Kernmagnetische Messungen an einem linearen Polyäthylen I. Spin-Gitter-Relaxationszeit T1 und Linienform1

Die Spin-Gitter-Relaxationszeit T1 und die Form des Kernresonanzsignals der Protonen eines linearen Polyäthylens (Marlex 50, Typ 15) wurden mit einer Impulsapparatur bei 28 MHz zwischen —150°C und + 180°C untersucht. Die Ergebnisse an festem und geschmolzenem Polyäthylen lassen sich durch drei verschiedene Bewegungsformen der Polyäthylen-Moleküle erklären, die mit steigender Temperatur angeregt werden. Die Theorie von SOLOMON 2 wird dazu auf einige anisotrope Bewegungen angewandt.

Frequency Dependence of Proton Spin Relaxation in Liquid Crystalline PAA

We report on measurements of the Larmor frequency dependence of the proton spin relaxation time T1 in the nematic and isotropic phase of p-azoxyanisole (frequency range: 3.8 kHz ≦ ωL/2 π≦75 MHz) . In both cases our results clearly support the Pincus-Cahane mechanism of spin relaxation by order fluctuations ("ωL−½-law") and exclude the alternative translational dif­fusion model (“ωL+½-law”). For the isotropic phase it was possible to evaluate the correlation time τ of the liquid crystalline order fluctuations from the observed T1 dispersion. As a function of the deviation ⊿ν=ν-νc from the critical nematic-isotropic transition temperature, νc= (136± 0.5)°C, we found τ=2.71·10-7-⊿ν-0.25s .

Kernmagnetische Relaxation und Korrelation im System Wasser - Sauerstoff

The magnetic interaction between the electronic magnetic dipole moment of molecular oxygen dissolved in water and water protons has been investigated by measuring the nuclear magnetic proton relaxation times and their dependence upon oxygen pressure (10–2—200 at), upon the proton LARMOR frequency (0.45 — 160 Mc) and upon temperature (20°C—300°C). The results are interpreted in terms of microscopic correlation times. The dipolar interaction, which is dominant, appears to be modulated in time mainly by the correlation time τS of the 02 electron spin. At 25°C we obtain τS = (1 ± 0.4) · 10-11 sec for the O2 spin correlation time and d= 2.87 ± 0.15 Å for the effective distance of nearest approach between electron and proton spin. The value for the translational correlation time TD &gt; 1.3·10-11 sec at 25°C, somewhat larger than in pure water, might suggest a weak, short-lived bonding between O2 and H2O.

NMR Pulsed Field Gradient Study of Self-Diffusion in the Isotropic Phase of the Liquid Crystals MBBA and EBBA

In refinement of a previous study made by Hayward and Packer, the self-diffusion coefficients D of the nematogen liquid crystals MBBA and EBBA were remeasured in the isotropic phase by means of the NMR pulsed field gradient technique. In particular, the diffusion measurements were made for the first time at different Larmor frequencies. A comparison with results obtained recently on the same samples by NMR T1 relaxation analysis reveals a severe discrepancy. Since the gradient method gives results in essential agreement with optical spectroscopies, the observed discrepancy must be attributed to shortages of the relaxation analysis (incorrect models, insufficient experimental accuracy). It is also shown that D depends more strongly on the molecular weight m than m-1/2 .

Proton Spin Relaxation in Reentrant Nematic Cyano -biphenyl Liquid Crystals

The frequency dependence of the longitudinal proton spin relaxation time T1 was measured by field-cycling and standard NMR techniques in the nematic, smectic and reentrant nematic mesophases of the reentrant liquid crystal 6OCB-8OCB. The results clearly demonstrate that, in contrast to conclusions reported in the literature, the underlying relaxation mechanisms are the same for the nematic and reentrant nematic order, but different in the nematic and smectic phase. In particular, at low frequencies the nematic and reentrant samples reveal a square-root dispersion profile (T1,~ ν½) characteristic for nematic director fluctuations, whereas the smectic samples show a dissimilar and only very narrow dispersion step. It can be attributed to a linear relaxation time increase (T1 ~ v1) expected for smectic-type order fluctuations. The experimental data are described and discussed in terms of four molecular processes, namely nematic or smectic order fluctuations, self-diffusion, rotational motions, and a resonant proton nitrogen coupling.

NMR Study of Collective Motions and Bending Rigidity in Multilamellar System of Lipid and Surfactant Bilayers

The frequency dependence of the longitudinal proton spin relaxation time T1 was measured by field-cycling and standard NMR techniques at different temperatures in the liquid crystalline lamellar phases of bilayer systems, composed of lipids, nonionic surfactants, and lipid-surfactant mixtures. We show by our data analysis, comparing various motional models such as layer undulations (LUs) and relaxation by translational diffusion mediated reorientations (TR), that collective layer undulations with their typical T1~ν behaviour determine the low frequency T1 dispersion in both unoriented and glass plate-oriented bilayer systems. The angular dependence of the T1 dispersion for the oriented bilayer system supports these findings and provides a more critical analysis of the two dimensional self-diffusion than in unoriented samples. The evaluated fitting parameters of the LU model allows, together with the measured second moment of the proton NMR signal for the lipid, calculation of the bending rigidity ϰc for these bilayers at different levels of hydration. The obtained values of ϰc turn out to be too large compared with the literature. However, using recent LU models (B. Halle) which include the obvious couplings between neighbouring bilayers at low Larmor frequencies, the corrected ϰc of the fully hydrated membrane systems are comparable to those obtained from the standard videooptical experiments. Therefore proton spin relaxation measure-ments at low Larmor frequencies with the field-cycling technique are a suitable means to determine the bending rigidity ϰc of model membrane systems at low hydrations and of systems containing surfactants.

NMR Field-Cycling Study of Rotational Flow and Viscosity in Nematic Liquid Crystals

A proton NMR method is described which enables rotational flow and viscosity measurements of low molecular weight ṉematic ḻiquid c̱rystals (NLC's). This is achieved by an extension of the common NMR field-cycling technique, namely by fast electronic switching of both the external magnetic field direction and strength. In thermodynamic equilibrium, the director of an NLC with positive diamagnetic anisotropy (Δχ > 0) orients parallel to the external magnetic field. Thus a change of this direction causes a reorientation process of the molecules to align to the new equilib­rium, which in low viscous systems in contrast to polymer liquid crystals is rather fast and hence requires fast field switching. We have studied systematically this response as a function of the initial field rotation angle 90 relative to the director for some homologous NLC's of the n-alkyl-cyano-biphenyl (nCB) series. It is shown that there exists a critical angle θcr in such a way that for θo < θcr, however (e.g. in the case of 5 CB θcr is ≈ 85 degrees) the viscoelastic behaviour is more complicated because of a coupling between flow and director gradients. The analysis of the alignment process by the changes of the proton line spectra also allows to determine the Leslie viscosities α1, α2, α3, α4 + α5, and the average Frank elastic constant K̄ by a single measurement.