Spectral studies of some hydroxy-derivatives of anthraquinones

The u.v., visible, and i.r. spectra of several hydroxy-anthraquinones are discussed and the bands are assigned. These bands are compared with those of anthracene and anthraquinone. The band at 207 nm. is assigned to a n-sigma* transition; the bands at 252, 272, and 326 nm. are assigned by measuring spectra in solvents of various polarities. The stability constant for the 12-dihydroxyanthraquinone-ethanol complex is obtained

A Robust Solution Procedure for Hyperelastic Solids with Large Boundary Deformation

Compressible Mooney-Rivlin theory has been used to model hyperelastic solids, such as rubber and porous polymers, and more recently for the modeling of soft tissues for biomedical tissues, undergoing large elastic deformations. We propose a solution procedure for Lagrangian finite element discretization of a static nonlinear compressible Mooney-Rivlin hyperelastic solid. We consider the case in which the boundary condition is a large prescribed deformation, so that mesh tangling becomes an obstacle for straightforward algorithms. Our solution procedure involves a largely geometric procedure to untangle the mesh: solution of a sequence of linear systems to obtain initial guesses for interior nodal positions for which no element is inverted. After the mesh is untangled, we take Newton iterations to converge to a mechanical equilibrium. The Newton iterations are safeguarded by a line search similar to one used in optimization. Our computational results indicate that the algorithm is up to 70 times faster than a straightforward Newton continuation procedure and is also more robust (i.e., able to tolerate much larger deformations). For a few extremely large deformations, the deformed mesh could only be computed through the use of an expensive Newton continuation method while using a tight convergence tolerance and taking very small steps.Comment: Revision of earlier version of paper. Submitted for publication in Engineering with Computers on 9 September 2010. Accepted for publication on 20 May 2011. Published online 11 June 2011. The final publication is available at http://www.springerlink.co

Band structure in classical field theory

Stability and instability bands in classical mechanics are well-studied in connection with systems such as described by the Mathieu equation. We examine whether such band structure can arise in classical field theory in the context of an embedded kink in 1+1 dimensions. The static embedded kink is unstable to perturbations but we show that if the kink is dynamic it can exhibit stability in certain parameter bands. Our results are relevant for estimating the lifetimes of various embedded defects and, in particular, loops of electroweak Z-string.Comment: 6 pages, 4 fig. Reference added, Fig. 3 updated with improved numerical code, minor comments added. Version to be published in Phys. Rev.

Polarographic Studies on Complexes of Pd(II) & Co(II) with Triethanolamine

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Dynamic Analysis Of A Novel Manpowered Transportation Vehicle With High Mechanical Efficiency

This paper evaluates the dynamics of a novel manpowered transportation vehicle. The vehicle has a novel mechanism that maximizes the mechanical input work and utilizes the weight of the rider for propulsion. The rider applies reciprocating stepping linear forces to drive chain and ratchet mechanism. The later transfer the reciprocating motion into a unidirectional rotational motion at the rear wheel to propel the vehicle. We analyzed the dynamics of the driving and transmission mechanism and derived the equations of motion, at first. Then, we evaluated the performance of the vehicle. Results show significant advantages of the novel driving mechanism

Solitary wave dynamics in time-dependent potentials

We rigorously study the long time dynamics of solitary wave solutions of the nonlinear Schr\"odinger equation in {\it time-dependent} external potentials. To set the stage, we first establish the well-posedness of the Cauchy problem for a generalized nonautonomous nonlinear Schr\"odinger equation. We then show that in the {\it space-adiabatic} regime where the external potential varies slowly in space compared to the size of the soliton, the dynamics of the center of the soliton is described by Hamilton's equations, plus terms due to radiation damping. We finally remark on two physical applications of our analysis. The first is adiabatic transportation of solitons, and the second is Mathieu instability of trapped solitons due to time-periodic perturbations.Comment: 38 pages, some typos corrected, one reference added, one remark adde

Organized Current Patterns in Disordered Conductors

We present a general theory of current deviations in straight current carrying wires with random imperfections, which quantitatively explains the recent observations of organized patterns of magnetic field corrugations above micron-scale evaporated wires. These patterns originate from the most efficient electron scattering by Fourier components of the wire imperfections with wavefronts along the $\pm 45^{\circ}$ direction. We show that long range effects of surface or bulk corrugations are suppressed for narrow wires or wires having an electrically anisotropic resistivity

Peripartum hysterectomy for cesarean section with morbidly adherent placenta: case series of 25 patients

Background: The current paper reports the outcome of case series of patients presented with placenta accreta confirmed histopathologicaly after management by peripartum hysterectomy.Methods: The study was set in Women’s Health Hospital, Assiut University, Egypt. This was a case series of 25 women presented with placenta accreta between May 2017 and April 2018. We included all pregnant women with placenta previa as diagnosed by ultrasound with suspicion of abnormal placentation by Doppler, confirmed intra-operatively undergoing either emergent or elective CS. All cases were performed by an expert team of obstetricians and anesthetists. Cesarean delivery was done under general anesthesia through pfannensteil incision. The primary outcome was the estimated intra-operative blood loss through assessment of amount of blood in the suction by ml, difference between the weight of surgical drapes and towels before and after operation.Results: Pre-operative Hb was 10.64±1.01 gm/dL and there was significant decline in the postoperative Hb reaching 8.36±1.21 gm/dL (p<0.001). The mean drop in Hb was 2.28±1.43gm/dL. Estimated intra-operative blood loss was 974.4±398.05 ml in the towels and 847.6±362.56 ml in the suction apparatus. The total blood loss was 1822±653.73 ml. The mean number of units of whole blood transfused was 2160.0±825.6 ml and fresh frozen plasma was 1010.0±349.7 ml. Regarding intra-operative complications, bladder injury was the most common one in 14 cases (56%), followed by ureteric injury in two cases (8%). Postoperative ICU admission was in 6 cases (24%) and the mean duration of hospital stay 12.44 ± 4.07 days. No cases of maternal mortality.Conclusions: In conclusion, peripartum hysterectomy is considered life-saving surgery in patients with placenta accreta