Detection of a Spin Accumulation in Nondegenerate Semiconductors

Electrical detection of a spin accumulation in a nondegenerate semiconductor using a tunnel barrier and ferromagnetic contact is shown to be fundamentally affected by the energy barrier associated with the depletion region. This prevents the ferromagnet from probing the spin accumulation directly, strongly suppresses the magnetoresistance in current or potentiometric detection, and introduces nonmonotonic variation of spin signals with voltage and temperature. Having no analogue in metallic systems, we identify energy mismatch as an obstacle for spin detection, necessitating control of the energy landscape of spin-tunnel contacts to semiconductors

Sign of tunnel spin polarization of low-work-function Gd/Co nanolayers in a magnetic tunnel junction

Magnetic tunnel junctions having a low-work-function Gd/Co nanolayer at the interface with an Al2O3 tunnel barrier are shown to exhibit both positive and negative values of the tunnel magnetoresistance. The sign of the tunnel spin polarization of the Gd/Co nanolayer electrode depends on the thickness of the Gd and Co layers, temperature, and applied voltage. This reflects the nature of the interaction between the conduction electrons of the rare-earth and transition metals. \u

Tunnel spin polarization of Ni80Fe20/SiO2 probed with a magnetic tunnel transistor

The tunnel spin polarization of Ni80Fe20/SiO2 interfaces has been investigated using a magnetic tunnel transistor (MTT). The MTT with a Ni80Fe20/SiO2 emitter shows a magnetocurrent of 74% at 100 K, corresponding to a tunnel spin polarization of the Ni80Fe20/SiO2 interface of 27%. This is only slightly lower than the value of 34% for Ni80Fe20/Al2O3 interfaces determined in similar MTT structures. This suggests that SiO2 can be applied in semiconductor spintronic devices, for example in ferromagnet/SiO2/Si tunnel contacts for spin injection.\ud \u

The parasiticidal effect of aureomycin (Lederle) on Babesia equi (Laveran 1899) in splenectomised donkeys

Veterinarians in countries where tick-borne diseases are prevalent are well acquainted with the difficulties encountered in the treatment of equine Babesiosis ( = Nuttaliosis). Affected animals do not respond satisfactorily to the present methods of treatment in all cases. In the systematic search for more effective drugs with a specific action against B. equi, Aureomycin, with its wide therapeutic spectrum, was tested for its babecidal action. The drug was kindly supplied by Lederle Laboratories Division, American Cyanamid Company, to whom it is desired to express our appreciation of their cooperation.The articles have been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

A surgical technique for the experimental reproduction of epididymitis in rams

A surgical technique is described for introducing a bacterial culture into the vas deferens of a ram close to the epididymis in such a manner that the infective material spreads to the lumen of the ductus epididymidis.The articles have been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Babesia thomasi Sp. Nov., an intra-erythrocytic parasite of the Cape dassie [Procavia capensis (Pallas)]

(1) A new species of protozoan parasite in the Cape dassie is described for which the name Babesia thomasi is proposed. (2) This parasite is only slightly pathogenic for normal animals but fatal for splenectomised Cape dassies. (3) A premunity develops in recovered animals. (4) Attempts at transmission to cattle and guinea-pigs failed. (5) The natural transmission is unknown. (6) The Cape dassie is not susceptible to Theileria parva infection.The articles have been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

The duration of immunity to pulpy kidney disease of sheep

It was shown that the immunity induced by a primary and secondary dose of antigen varying from 25 to 135 Lf APT, protected sheep for only about nine weeks. Any booster dose given before a year after the primary injection resulted in protective titres lasting for periods up to about 20 weeks. When a sound basic immunity is established, e.g. with two doses of 135 Lf, sheep are protected to the same extent by a large (135 Lf) or small (25 Lf) booster dose given one year after the primary injection. The protection thus effected lasts for at least one year. When sheep with a sound basic immunity receive a booster of 135 Lf after one year and a second booster of 135 Lf after a further year, they are protected against pulpy kidney disease for at least three years following the last injection. A single injection of epsilon toxoid in Freund's complete or incomplete adjuvant protects sheep for at least two years.The journals have been scanned in colour with a HP 5590 scanner; 600 dpi. Adobe Acrobat v.11 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.ab201

The production of a basic immunity against pulpy kidney disease

A single dose of alum-precipitated epsilon toxoid (APT) produces only a transitory immunity when given to fully susceptible sheep. A maximal immunity response is brought about by two injections each containing 90 Lf toxoid. The interval between the primary and secondary stimuli may vary from two to six weeks without influencing the end result.The journals have been scanned in colour with a HP 5590 scanner; 600 dpi. Adobe Acrobat v.11 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.ab201

The epidemiology of bacterial infection of the genitalia in rams

The interrelationship between the various bacteria isolated from the genital tract of rams and their host animals was studied. The pathogenicity of the different isolates varied. Several of these bacteria could be cultured in a medium consisting of a suspension of pen floor debris solidified with agar, while many organisms survived in the suspension for 10 days. Epidemiological investigations showed that rams kept under intensive systems were subjected to large-scale invasion of their genitalia by bacteria which led to infection of the accessory glands and orchitis and epididymitis. Apart from the preputial cavity, some rams kept on open range were entirely free of bacterial infection of their genitalia, and those that did have bacteria in the deeper parts of their genitalia had a very significantly lower incidence of pathological lesions of their genitalia. Finding bacteria and neutrophils in semen is consistent with the epidemiological findings.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format