Entrapment of magnetic micro-crystals for on-chip electron spin resonance studies

On-chip Electron Spin Resonance (ESR) of magnetic molecules requires the ability to precisely position nanosized samples in antinodes of the electro-magnetic field for maximal magnetic interaction. A method is developed to entrap micro-crystals containing spins in a well defined location on a substrate's surface. Traditional cavity ESR measurements are then performed on a mesoscopic crystal at 34 GHz. Polycrystalline diluted Cr$^{5+}$ spins were entrapped as well and measured while approaching the lower limit of the ESR sensitivity. This method suggests the feasibility of on-chip ESR measurements at dilution refrigerator temperatures by enabling the positioning of samples atop an on-chip superconducting cavity.Comment: to appear in Journal of Applied Physic

Spin-Orbit Coupling Fluctuations as a Mechanism of Spin Decoherence

We discuss a general framework to address spin decoherence resulting from fluctuations in a spin Hamiltonian. We performed a systematic study on spin decoherence in the compound K$_6$[V$_{15}$As$_6$O$_{42}$(D$_2$O)] $\cdot$ 8D$_2$O, using high-field Electron Spin Resonance (ESR). By analyzing the anisotropy of resonance linewidths as a function of orientation, temperature and field, we find that the spin-orbit term is a major decoherence source. The demonstrated mechanism can alter the lifetime of any spin qubit and we discuss how to mitigate it by sample design and field orientation.Comment: submitte

Simulating spatial variability of cereal yields from historical yield maps and satellite imagery

[Abstract]: The management of spatial variability of crop yields relies on the availability of affordable and accurate spatial data. Yield maps are a direct measure of the crop yields, however, costs and difficulties in collection and processing to generate yield maps results in poor availability of such data in Australia. In this study, we used historical mid-season normalised difference vegetation index (NDVI), generated from Landsat imagery over 4 years. Using linear regression model, the NDVI was compared to the actual yield map from a 257 ha paddock. The difference between actual and predicted yield showed that 77% and 93% of the paddock area had an error of <20% and <30%, respectively. The linear model obtained in the paddock was used to simulate crop yield for an adjoining paddock of 162 ha. On an average of 4 years, the difference between actual and simulated yield showed that 87% of the paddock had an error of <20%. However, this error varied from season to season. Paddock area with <20% error increased exponentially with decreasing in-crop rainfall between anthesis and crop maturity. Furthermore, the error in simulating crop yield also varied with the soil constraints. Paddock zones with high concentrations of subsoil chloride and surface soil exchangeable sodium percentage generally had higher percent of error in simulating crop yields. Satellite imagery consistently over-predicted cereal yields in areas with subsoil constraints, possibly due to chloride-induced water stress during grain filling. The simulated yield mapping methodology offers an opportunity to identify within-field spatial variability using satellite imagery as a surrogate measure of biomass. However, the ability to successfully simulate crop yields at farm scale or regional scale requires wider evaluation across different soil types and climatic conditions

The Relation of Serum Anti-Mullerian Hormone with Polycystic Ovary Syndrome: Correlation with Clinical and Hormonal Parameters

Background: Polycystic ovary syndrome PCOS) is an endocrine disorder affects 5-10% of all women. The antimullerian hormone (AMH) secreted from granulose cells and is a marker of follicle pool size, in recent studies of PCOS the serum AMH levels were elevated two to threefold.Objective: to compare AMH between women with and without PCOS, and to investigate if any relationship of AMH to the clinical and hormonal parameters in both groups.Design: Prospective comparative and analytic study.Setting: In fertility center of Al-Sader medical city in Najaf.Material and methods: A total of 86 subfertile women divided into PCOS group (56) and control non-PCOS group (30). The PCOS group diagnosed according to Rotterdam consensus meeting definition (2004). For both groups during early follicular phase transvaginal sonography was performed. Blood samples were collected for: FSH, LH, testosterone, prolactin and AMH levels.Results: There was highly significant increase level of AMH in PCOS than in non-PCOS group. From 56 patients with PCOS, 28 patients took metformin treatment for at least 2 months and the other 28 patients on no treatment. There was no significant differences in all hormonal parameters between them. There were no significant correlations between the AMH and all the parameters in both PCOS and controlsConclusion: Increased AMH levels in PCOS possibly due to increased number of small antral follicles. However, there was no correlation between the AMH and other clinical or hormonal parameters. Large scale studies are needed to define the metformin effect on hormonal outcome. Keywords:- PCOS, AM

Study of the local field distribution on a single-molecule magnet-by a single paramagnetic crystal; a DPPH crystal on the surface of an Mn12-acetate crystal

The local magnetic field distribution on the subsurface of a single-molecule magnet crystal, SMM, above blocking temperature (T >> Tb) detected for a very short time interval (~ 10-10 s), has been investigated. Electron Paramagnetic Resonance (EPR) spectroscopy using a local paramagnetic probe was employed as a simple alternative detection method. An SMM crystal of [Mn12O12(CH3COO)16(H2O)4].2CH3COOH.4H2O (Mn12-acetate) and a crystal of 2,2- diphenyl-1-picrylhydrazyl (DPPH) as the paramagnetic probe were chosen for this study. The EPR spectra of DPPH deposited on Mn12-acetate show additional broadening and shifting in the magnetic field in comparison to the spectra of the DPPH in the absence of the SMM crystal. The additional broadening of the DPPH linewidth was considered in terms of the two dominant electron spin interactions (dipolar and exchange) and the local magnetic field distribution on the crystal surface. The temperature dependence of the linewidth of the Gaussian distribution of local fields at the SMM surface was extrapolated for the low temperature interval (70-5 K)

The Electrical Properties of Poly(o- toluidine) Doped with DBSA Blend with Polyethylene Oxide PEO as Nano Conducting Polyblend

Poly (o-toluidine) (POT ) doped with Dodecyl benzene Sulfonic Acid DBSA synthesis by chemical polymerization method using ammonium persulphate as oxidizing gent.  Nano Conducting polyblends POT-DBSA/POE  films were prepared by mixed different ratio  (0 – 10%, 150%, 25%, 35% ,45%and 50%) of polyethylene  oxide  polyethylene oxide (PEO)   with conducting polymer (POT-DBSA) and prepared by spin coating method . Morphology and diameters of the  nanofibers were studied by Atomic Force  Microscope  (AFM).  The  diameter  of  nanfiber  was  about  85.49  nm  (at  15 wt%  PEO concentration)  and  increased  with  increasing  concentration  to  105  nm  (at  50  wt%  PEO concentration). . The electrical properties of conducting polyblends POT-DBSA/POE  were  measured by two probes  method. I-V  characteristic of  these films at different weigh ratio of POE were investigated .They showed  ohmic behavior at all applied voltages . The electrical conductivity increases as POE increase from7.2 x10- 7 S/cm at 0% to  4.48 x10- 5 S/cm at 50% ..The activation energy at temperature  were found at rang (293-353)K are also investigated . Keywords: key words, conducting polyblend, poly (O-toluden)(POT), polyethylene  oxide  polyethylene oxide (POE),  ,electrical properties