On the importance of sensor height variation for detection of magnetic labels by magnetoresistive sensors.

Magnetoresistive sensors are widely used for biosensing by detecting the signal from magnetic labels bound to a functionalized area that usually covers the entire sensor structure. Magnetic labels magnetized by a homogeneous applied magnetic field weaken and strengthen the applied field when they are over and outside the sensor area, respectively, and the detailed origin of the sensor signal in experimental studies has not been clarified. We systematically analyze the signal from both a single sensor stripe and an array of sensor stripes as function of the geometrical parameters of the sensor stripes as well as the distribution of magnetic labels over the stripes. We show that the signal from sensor stripes with a uniform protective coating, contrary to conventional wisdom in the field, is usually dominated by the contribution from magnetic labels between the sensor stripes rather than by the labels on top of the sensor stripes because these are at a lower height. We therefore propose a shift of paradigm to maximize the signal due to magnetic labels between sensor stripes. Guidelines for this optimization are provided and illustrated for an experimental case from the literature.

TEM analyses of synthetic anti-ferromagnetic (SAF) nanoparticles fabricated using different release layers.

This paper investigates the structural characteristics of templated synthetic anti-ferromagnetic (SAF) magnetic nanoparticles fabricated on two different release layers. When copper was used as the latter, the layered structure of the SAFs was found to be disrupted with wavy multi-layers due to the formation of copper grains from the release layer. By introducing oxygen into the copper release layer before the deposition of the film, the topography of the oxidized copper grains was effectively controlled. This led to the fabrication of SAF nanoparticles with flat multi-layers.

Histopathological study of five cases with sporadic meningioangiomatosis.

We report five cases of sporadic meningioangiomatosis, three males and two females, ranging in age from 12 to 36 years at diagnosis. The lesion was found incidentally by MRI after a head trauma in one case; the other four subjects had a seizure disorders, which improved following surgical resection of the cortical lesions. Grossly, the lesionectomy specimens were of a whitish color and firm consistency. Histological examination revealed that the lesions were confined to the cortex with focal involvement of the overlying leptomeninges, and revealed unifying features of meningioangiomatosis, such as proliferating microvessels with perivascular cuffs of spindle-cell proliferation within the cortex. Two cases had numerous calcifications; one was associated with a prominent fibrocalcifying component. Immunostaining results were variable among the cases. Only vimentin was consistently positive. Some of the spindle cells were weak positive for EMA in two cases. Immunoreactions with anti-CD34 detected within the cytoplasm of the spindle cells were observed in three of the five cases. The Ki-67 proliferation index of all the cases was very low, less than 0.1%. Neurofibrillary tangles were identified in only one of the five cases using the Bodian and immunostaining methods. These findings indicate that meningioangiomatosis lesions show a wide range of clinicopathological features, making diagnosis difficult. A histopathological spectrum and differential diagnoses were discussed with a review of the literature. Since this lesion is a distinct clinicopathological entity and hamartomatous in nature, it is important to make a correct diagnosis in order to avoid further aggressive treatment.

[Characteristics of vestibular-ocular reflex in guinea pigs during eccentric sinusoidal rotation].

AIM: To observe the characteristics of vestibular-ocular reflex (VOR) of guinea pigs during eccentric sinusoidal rotation in different frequencies and radius, and compare them with that during axis rotation, obtain the parameters which reflect otolith functions, and provide experimental evidence for the establishment of otolith function test. METHODS: Guinea pigs were placed in axis of rotation and in an heading out eccentric position apart from rotation axis of 330 mm, 660 mm and 990 mm respectively, their VOR were recorded and compared under stimulus of sinusoidal rotations in the frequencies of 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6 Hz with the peak velocity of 60 degrees/s in each position. RESULTS: Both frequency and eccentric radius had significant effects on the VOR gain, it increased with the increase of frequencies and radius. The largest increase of the gain occurred at the frequencies of 0.3 and 0.4Hz, and no significant changes were observed above these frequencies. CONCLUSION: Enhancement ratio (ER) of VOR gain can reflect the extent of its increase with radius, and can be used as an index of otolith function, the stimulus profile of eccentric rotation at frequency of 0.4Hz and radius of 990mm is recommended as the stimulus profile for the otolith function test.