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J Bokor

Publications and source records attributed to J Bokor.

At least 19 recordsLinked to original sources
PubMed2005

Fabrication of large number density platinum nanowire arrays by size reduction lithography and nanoimprint lithography.

Large number density Pt nanowires with typical dimensions of 12 microm x 20 nm x 5 nm (length x width x height) are fabricated on planar oxide supports. First sub-20 nm single crystalline silicon nanowires are fabricated by size reduction lithography, and then the Si nanowire pattern is replicated to produce a large number of Pt nanowires by nanoimprint lithography. The width and height of the Pt nanowires are uniform and are controlled with nanometer precision. The nanowire number density is 4 x 10(4) cm(-1), resulting in a Pt surface area larger than 2 cm(2) on a 5 x 5 cm(2) oxide substrate. Bimodal nanowires with different width have been generated by using a Pt shadow deposition technique. Using this technique, alternating 10 and 19 nm wide nanowires are produced.

Journal Article↗
PubMed2005

Integration of scanning probes and ion beams.

We report the integration of a scanning force microscope with ion beams. The scanning probe images surface structures non-invasively and aligns the ion beam to regions of interest. The ion beam is transported through a hole in the scanning probe tip. Piezoresistive force sensors allow placement of micromachined cantilevers close to the ion beam lens. Scanning probe imaging and alignment is demonstrated in a vacuum chamber coupled to the ion beam line. Dot arrays are formed by ion implantation in resist layers on silicon samples with dot diameters limited by the hole size in the probe tips of a few hundred nm.

Bismuth↗
PubMed2000

Transmission phase gratings for EUV interferometry.

The performance of the recently developed EUV phase-shifting point diffraction interferometer (PS/PDI) depends heavily on the characteristics of the grating beamsplitter used in the implementation. Ideally, such a grating should provide throughput of better than 25% and diffraction efficiency, defined as the ratio of the first-diffracted-order power to the zero-order power, variable in the range from approximately 10 to 500. The optimal method for achieving these goals is by way of a phase grating. Also, PS/PDI system implementation issues favor the use of transmission gratings over reflection gratings. Here, the design, fabrication, and characterization of a recently developed transmission phase grating developed for use in EUV interferometry is described.

Journal Article↗
PubMed1990

[Atypical lumbar and nerve-root pain associated with the HTLV-1 virus].

The human retrovirus HTLV-1 (Human T-cell Lymphotrophic Virus) is responsible for malignant proliferations of mature T lymphocytes. It is also now implicated in neurological disorders dominated by spastic paraplegia. A study of 140 cases of lumbar and root pain enabled us to identify 8 of apparently idiopathic atypical lumbar and root pain which led to the discovery of a positive HTLV-1 serology performed routinely. These cases were remarkable in terms of the rarity and minimal extent of spinal cord signs and of Lasegue's sign, their duration of more than a year and the existence of neurological signs indicative of central involvement. In 2 patients there was secondary progression to a spastic paraparesis. It would appear that the neurotropism of HTLV-1 virus is not limited to the central nervous system but that it can also involve the peripheral nervous system as indicated by certain cases in the literature as well as those collected in Martinique, an endemic area for the virus. Rheumatologists should be aware of this possibility when confronted with such cases of atypical lumbar and root pain and should seek the existence of an HTLV-1 virus infection among other viral etiologies, in particular when the patient concerned comes from an endemic area.

Adult↗
PubMed1988

[Recurrences of supratentorial meningiomas. Apropos of 17 cases].

17 cases of recurrent meningiomas observed during a 10 years period are reviewed. Meningiomas with a second localisation different from the first were excluded from the study. The tumor recurrence occurred mostly during the first five years after the surgical procedure. One case with femoral and pulmonary metastasis is described. Several factors may play a role in the genesis of the recurrence: age, sex, the tumor localisation, CT scan, the importance of the tumor ablation, the histology. In almost all cases a radiotherapy was carried out after the second surgical procedure. This retrospective study suggests the need for multifactorial prospective analysis with clinical, paraclinical and fundamental factors. Such a study would be useful to precise the natural history of meningiomas.

Adult↗
PubMed1988

[Cerebrovascular complications of sickle-cell anemia].

Cerebrovascular disorders are frequent in sickle-cell anemia. They occur mainly in homozygous children. Traditionally, they were believed to result from an arteriolar sickle-cell thrombosis, the "sludge" phenomenon, which is generally responsible for sickle cell anemia disorders. It is now well known that several other kinds of cerebral damages are involved such as moya-moya syndrome, cerebral hemorrhage, subdural hematoma, extra-dural hematoma and cerebral thrombophlebitis. In this disease, the identification of these different processes cannot be always made by a simple clinical examination. However, specific therapies are sometimes necessary, such as neurosurgical intervention in the case of aneurysm or hematoma, and, according to some authors, the necessity of repeated appropriate transfusions, in the case of moya-moya. So it is imperative to carry out without delay a complete neuroradiological assessment of the lesions. At present, the most widely accepted theory to explain the arteriolar lesions, is that they result from a sickle-cell thrombosis of the vasa-vasorum, but, we think it is not the only valid hypothesis and we think that other phenomena may be involved with a genetic factor (patients with connective tissue disorders may have a particular genotype), and with infectious or autoimmune or coagulation disorders, the latter being frequently observed in this disease.

Adolescent↗
PubMed1986

Adrenergic and cholinergic innervation of the smooth and striated muscle components of the urethra from patients with spinal cord injury.

The adrenergic and cholinergic innervation of the smooth and striated muscle components of the urethra from spinal cord injury patients with detrusor sphincter dyssynergia were investigated neurochemically and histochemically. Catecholamine fluorescence histochemistry provided no evidence for the presence of adrenergic nerves associated with the skeletal muscle. The noradrenaline content of this region probably reflects the endogenous levels in adrenergic nerves associated with the blood vessels supplying the skeletal muscle. Choline acetyltransferase activity in the skeletal muscle was significantly lower in patients with cervical lesions than in those with thoracic lesions (p less than 0.01). The noradrenaline content of the smooth muscle was significantly lower in cervical lesions than in thoracic lesions in both the mid (p less than 0.02) and the distal (p less than 0.001) regions of the urethra. The proximal region revealed similar noradrenaline levels in both groups of spinal cord injury patients. The results are discussed in relation to the role of the autonomic nervous system in the control of voiding and to the presence of increased sympathetic outflow in patients with spinal cord lesions at higher levels.

Adolescent↗
PubMed1986

[Dysmorphic syndrome and vascular dysplasia: an atypical form of type IV Ehlers-Danlos syndrome].

A 29 year old woman was hospitalized for the successive onset of extremely serious vascular accidents: rupture of the gastro-duodenal artery, aneurysm of the posterior tibial artery, discovery of bilateral carotid and vertebral aneurysm with development of a carotid-cavernous fistula. The patient had a very unusual morphotype with dwarfism, white hair and alopecia. Histological investigations failed to reveal atheromatous lesions and by contrast showed involvement of the skin (dermal atrophy) and in the blood vessels fibro-dysplasia of the media. This picture was suggestive of a vascular form of Ehlers-Danlos disease (Sack's syndrome or type IV Ehlers-Danlos disease). This syndrome is characterized by minor skin or joint manifestations replaced by arterial accidents (arterial rupture or development of aneurysms). The etiology is faulty maturation of procollagen III and the diagnosis is based upon fibroblast culture.

Abnormalities, Multiple↗