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Experiments were conducted to demonstrate the creation and observation of para-hydrogen-induced polarization in heterogeneous hydrogenation reactions. The results suggest that mechanism of heterogeneous hydrogenation reactions involving immobilized metal complexes could be potentially developed into a practical tool for producing catalyst-free fluids with highly polarized nuclear spins for a broad range of hyperpolarized NMR and MRI applications.

We demonstrate a nuclear magnetic resonance (NMR) experiment using continuous flow in a microfluidic channel for studying the transfer of spin coherence in nonequilibrium chemical processes. We use the principle of remote detection, which involves spatially separated NMR encoding and detection coils. As an example, we provide the map of chemical shift correlations for the amino acid alanine as it transitions from the zwitterionic to the anionic form. The presented method uniquely allows for tracking the migration of encoded spins during the course of any chemical transformation and can provide useful information about reaction mechanisms.

Coexistence of spontaneous magnetization and polarization is a key phenomenon in multiferroic materials whereas coupling among these order parameters is anticipated to play a vital role in modern day engineering devices and information technology. In this context, Mn substituted BiFeO3 was synthesized using sol-gel accompanying auto-combustion method. X-ray diffraction of the calcined BiFe1−xMnxO3 samples exhibited a crystalline nature and phase purity of the samples. Among the samples, BiFe0.8Mn0.2O3 depicted more stable rhombohedral structure as compared to BiFeO3, whereas mixed phases of orthorhombic and monoclinic were observed in BiFe1−xMnxO3 at 0.4 ≤ x ≤ 1.0. Surface morphology, as seen using a field emission electron microscope, revealed decreasing granular size which interpreted modified magnetic attributes examined by vibrating sample magnetometer for specific Mn contents. Elemental wt% were confirmed by energy dispersive X-ray spectroscopy. To extract the optimized results from Mn substituted BiFeO3, magnetodielectric coupling was examined as well under 6 kOe applied magnetic field which declared BiFe0.8Mn0.2O3 as the most optimized composition. Hence, this research work has opened the way for the material scientists and engineers to pursue more efficient multiferroics. It is an effective way to rectify various issues relevant to device applications like quick switching, magnetically controlled supercapacitors and designing fast and higher density data storage devices that is magnetoelectric random-access memories. [ABSTRACT FROM AUTHOR]

Impedance spectroscopy (IS) is a non-destructive technique used for obtaining valuable information about bulk conductivities, dielectric constants, phase composition and grain boundaries of important ceramic materials, amongst many others. We obtained Nyquist plots for four different hot-pressed Si[sub 3]N[sub 4] samples in two different frequency regimes: 1 Hz to 30 MHz and 1 kHz to 100 kHz. The information obtained was compared against results from scanning electron microscopy (SEM) and X-ray diffraction (XRD). The limitations of the frequency response techniques are also discussed. [ABSTRACT FROM AUTHOR]

Abstract: Discrete and jerky jumps during the process of magnetization reversal in ferromagnetic systems cause Barkhausen intermittency. We have investigated critical scaling behavior of the Barkhausen avalanche of 2-dimensional γ-Fe4N thin films using a magneto-optic microscope magnetometer (MOMM) capable of time-resolved magnetic domain images. A statistical analysis of the fluctuating size of Barkhausen jumps from numerous repetitive experiments shows a power-law scaling behavior in the ferromagnetic iron nitride system exhibiting a critical exponent value of within the experimental error. The value of critical exponent is found to manifest universality irrespective of the degree of texture of the film induced by annealing temperature. [Copyright &y& Elsevier]

The synthesis, characterisation and thermal and photochemical reactivity of Ru(CO)2(PPh3)(dppe) 1 towards hydrogen are described. Compound proved to exist in both fac (major) and mer forms in solution. Under thermal conditions, PPh3 is lost from 1 in the major reaction pathway and the known complex Ru(CO)2(dppe)(H)2 2 is formed. Photochemically, CO loss is the dominant process, leading to the alternative dihydride Ru(CO)(PPh3)(dppe)(H)2 3. The major isomer of 3, viz. 3a, contains hydride ligands that are trans to CO and trans to one of the phosphorus atoms of the dppe ligand but a second isomer, 3b, where both hydride ligands are trans to distinct phosphines, is also formed. On the NMR timescale, no interconversion of 3a and 3b was observed, although hydride site interchange is evident with activation parameters of DeltaH(double dagger) = 95 +/- 6 kJ mol(-1) and DeltaS(double dagger) = 26 +/- 17 J K(-1) mol(-1). Density functional theory confirms that the observed species are the most stable isomeric forms, and suggests that hydride exchange occurs via a transition state featuring an eta2-coordinated H2 unit.