Importance of spin-orbit interaction for the electron spin relaxation in organic semiconductors.

Despite the great interest organic spintronics has recently attracted, there is only a partial understanding of the fundamental physics behind electron spin relaxation in organic semiconductors. Mechanisms based on hyperfine interaction have been demonstrated, but the role of the spin-orbit interaction remains elusive. Here, we report muon spin spectroscopy and time-resolved photoluminescence measurements on two series of molecular semiconductors in which the strength of the spin-orbit interaction has been systematically modified with a targeted chemical substitution of different atoms at a particular molecular site. We find that the spin-orbit interaction is a significant source of electron spin relaxation in these materials.

Analysis of Pressure Variations in a Low-Pressure Nickel-Hydrogen Battery- Part 2: Cells with Metal Hydride Storage.

A sub-atmospheric pressure nickel hydrogen (Ni-H(2)) battery with metal hydride for hydrogen storage is developed for implantable neuroprosthetic devices. Pressure variations during charge and discharge of the cell are analyzed at different states of charge and are found to follow the desorption curve of the pressure composition isotherm (PCI) of the metal hydride. The measured pressure agreed well with the calculated theoretical pressure based on the PCI and is used to predict the state of charge of the battery. Hydrogen equilibration with the metal hydride during charge/discharge cycling is fast when the pressure is in the range from 8 to 13 psia and slower in the range from 6 to 8 psia. The time constant for the slower hydrogen equilibration, 1.37h, is similar to the time constant for oxygen recombination and therefore pressure changes due to different mechanisms are difficult to estimate. The self-discharge rate of the cell with metal hydride is two times lower in comparison to the cell with gaseous hydrogen storage alone and is a result of the lower pressure in the cell when the metal hydride is used.

Analysis of Pressure Variations in a Low-Pressure Nickel-Hydrogen Battery - Part 1.

A low pressure nickel-hydrogen battery using either a metal hydride or gaseous hydrogen for H(2) storage has been developed for use in implantable neuroprosthetic devices. In this paper, pressure variations inside the cell for the gaseous hydrogen version are analyzed and correlated with oxygen evolution side reaction at the end of charging, the recombination of oxygen with hydrogen during charging and a subsequent rest period, and the self-discharge of the nickel electrode. About 70% of the recombination occurred simultaneously with oxygen evolution during charging and the remaining oxygen recombined with hydrogen during the 1(st) hour after charging. Self-discharge of the cell varies linearly with hydrogen pressure at a given state of charge and increased with increasing battery charge levels. The coulometric efficiency calculated based on analysis of the pressure-time data agreed well with the efficiency calculated based on the current-time data. Pressure variations in the battery are simulated accurately to predict coulometric efficiency and the state of charge of the cell, factors of extreme importance for a battery intended for implantation within the human body.

Ligamentotaxis for Barton's and paediatric distal radial fractures.

PURPOSE: To establish a consensus regarding immobilisation of the wrist following reduction of Barton's and paediatric distal radial fractures. METHODS: Questionnaires were distributed to orthopaedic surgeons at the European Federation of National Associations of Orthopaedics and Traumatology meeting in Lisbon in 2005. Questions included the surgeon's country of practice, hospital, professional grade, years of experience, sub-specialty, and preferred position of wrist immobilisation after (1) a volar Barton's fracture, (2) a dorsal Barton's fracture, (3) a paediatric Salter-Harris type-II injury to the distal radius with volar displacement, and (4) the same injury but with dorsal displacement. RESULTS: Of 148 questionnaires distributed, 118 were returned. The specialist-to-trainee ratio was 45:73. In volar Barton's fractures, only 20% (29% specialists and 15% trainees) would immobilize the wrist in palmar flexion, as per recommendations. In dorsal Barton's fractures, only 25% (33% specialists and 21% trainees) would immobilize the wrist in dorsiflexion, as per recommendation. In paediatric Salter Harris type-II injury to the distal radius with volar displacement, 87% (100% specialists and 79% trainees) would immobilize the wrist in dorsiflexion or in a neutral position, as per recommendation. In the same injury but with dorsal displacement, 84% (89% specialists and 81% trainees) would immobilize the wrist in palmar flexion or in a neutral position, as per recommendation. In all 4 types of fractures, 26% to 30% of respondents would immobilize the wrist in a neutral position. CONCLUSION: Most respondents deviate from the recommended immobilisation positions in treating Barton's fractures. Understanding of the anatomy or biomechanics of ligamentotaxis are crucial for conservative treatments.

Decision making on timing of surgery for hip fracture patients on clopidogrel.

Patients taking clopidogrel who sustain a fractured neck of femur pose a challenge to orthopaedic surgeons. The aim of this study was to determine whether delay to theatre for these patients affects drop in haemoglobin levels, need for blood transfusion, length of hospital stay and 30-day mortality. A retrospective review of all neck of femur patients admitted at two centres in the North East of England over 3 years revealed 85 patients. Patients were divided into two groups depending on whether they were taking clopidogrel alone (C) or with aspirin (CA). Haemoglobin drop was significantly different in the CA group that was operated on early (CA1) versus the group for which surgery was delayed by over 48 hours (CA2): 3.3g/dl and 1.9g/dl respectively (p=0.01). The mean inpatient stay in group C was 35.9 days while in group CA it was 19.9 days (p=0.002). The mean length of stay in group CA2 (26.7 days) was significantly longer than for CA1 patients (14.1 days) (p=0.01). There were no significant differences in mortality or wound complications. Hip fracture patients on clopidogrel can be safely operated on early provided they are medically stable. Bleeding risk should be borne in mind in those patients on dual therapy with aspirin.

Outcome of lumbar spinal fusion surgery in obese patients: a systematic review and meta-analysis.

The aim of this study was to determine whether obesity affects pain, surgical and functional outcomes following lumbar spinal fusion for low back pain (LBP). A systematic literature review and meta-analysis was made of those studies that compared the outcome of lumbar spinal fusion for LBP in obese and non-obese patients. A total of 17 studies were included in the meta-analysis. There was no difference in the pain and functional outcomes. Lumbar spinal fusion in the obese patient resulted in a statistically significantly greater intra-operative blood loss (weighted mean difference: 54.04 ml; 95% confidence interval (CI) 15.08 to 93.00; n = 112; p = 0.007) more complications (odds ratio: 1.91; 95% CI 1.68 to 2.18; n = 43858; p < 0.001) and longer duration of surgery (25.75 mins; 95% CI 15.61 to 35.90; n = 258; p < 0.001). Obese patients have greater intra-operative blood loss, more complications and longer duration of surgery but pain and functional outcome are similar to non-obese patients. Based on these results, obesity is not a contraindication to lumbar spinal fusion.

Delayed ulnar nerve palsy secondary to ulnar artery pseudoaneurysm distal to Guyon's canal following penetrating trauma to the hand.

Compression of the ulnar nerve in Guyon's canal is an uncommon phenomenon. Reports of ulnar nerve palsy secondary to ulnar artery pseudoaneurysm at this anatomical location are very rare and equivalent pathology just distal to this site is unheard of. Here we present such a case, which featured a delayed onset of symptoms. This followed penetrating trauma to the hand. Our methods for diagnosis, operative planning and surgical treatment are included.

Is gender difference in postnatal thyroid growth associated with specific expression patterns of androgen and estrogen receptors?

Variations in sex steroids bioavailability were linked to the gender difference in the growth of thyroid glands of neonatal rats. In the present study we tested androgen receptor (AR) and estrogen receptor (ER) concentrations by ligand binding assay, and expression of their genes by RT-PCR and Western blot in the thyroid glands of neonatal rats. AR concentration remained elevated from postnatal day (PND) 10 onwards in males, whereas it decreased by PND 20 in females. AR mRNA and protein expressions were higher in males than females, which increased by PND 10, decreased after PND 15 and reached the nadir by PND 20. ER concentration increased by PND 10 and decreased thereafter in both sex. ERα mRNA expression diminished by PND 15 in both sex; while ERß mRNA decreased by PND 15 to reach the nadir by PND 20 in males, it was augmented by PND 10 in females to reach the peak by PND 15 and diminished by PND 20. ERα protein expression increased by PND 10 and remained elevated till PND 20 in both sex. ERß protein expression in males increased by PND 10 and decreased by PND 20, while it remained static up to PND 15 and decreased in females. Testosterone stimulated [(3)H]-thymidine uptake and the expression of IGF-1 and NIS genes in thyrocytes of both sex in vitro, while estradiol stimulated them in females but not in males. We conclude that androgens influence the growth and differentiation of thyrocytes through augmented expression of AR, IGF-1 and NIS in either sex, whereas estrogen imparts the gender difference, which may be at a level beyond the expression of ERs.

[5,10,15,20-Tetrakis(2-thienyl)-porphyrinato]zinc(II).

In the title complex, [Zn(C(36)H(20)N(4)S(4))], the Zn(II) ion occupies a special position on an inversion centre with four-coordinate geometry. The porphyrin ring shows a wave-like conformation, with the closest interporphyrin plane separation being 3.60 (6) A. The two disordered thienyl groups are inclined with respect to the porphyrin plane at angles of 70 (4) and 67 (2) degrees.