Swords to plowshares: Shock wave applications to advanced lithography

xtreme ltra iolet ithography (EUVL) seeks to apply radiation in a wavelength region centered near 13 nm to produce microcircuits having feature sizes 0.1 micron or less. A critical requirement for the commercial application of this technology is the development of an economical, compact source of this radiation which is suitable for lithographic applications. A good candidate is a laser-plasma source, which is generated by the interaction of an intermediate intensity laser pulse (up to 10¹² W/cm²) with a metallic target. While such a source has radiative characteristics which satisfy the needs of an EUVL source, the debris generated during the laser-target interaction strikes at the economy of the source. Here, we review the use of concepts and computer modeling, originally developed for hypervelocity impact analysis, to study this problem.     

Induction of superoxide dismutase isozymes by tumor necrosis factor-alpha and lipopolysaccharide in cultured normal and hyperplastic gingival fibroblasts

We studied 722 reexcision scars of benign and malignant lesions (except melanocytic lesions) excised over a 24-month period. The formalin-fixed, paraffin-embedded tissue sections were examined histologically and immunohistochemically. The histological features of melanocytic hyperplasia were present in 59 cases (8%), 56 from the sun-exposed skin of the face and neck and three from the trunk [p < 0.00001]. The most common sites were the nose and lower eyelids, but the forehead was also frequently involved. Of the 59 patients, 41 were women (p < 0.0001). Basal cell carcinoma was the most frequent original lesion in both sexes (80%). No melanocytic hyperplasia was found in 663 cases (298 on the trunk and extremities and 365 on the head and neck). We have seen this reaction pattern following reexcision of melanocytic lesions as well. Thus, interpreting reexcision margins when lentigo maligna or similar lesions are reexcised may be fraught with difficulty. It is important for pathologists and dermatopathologists to recognize this phenomenon because histologically the presence of increased numbers of large melanocytes could be misinterpreted as melanoma in situ.     

Numerical and experimental studies of high-velocity impact fragmentation

Developments are reported in both numerical and experimental capabilities for characterizing the debris spray produced in penetration events. We have performed a series of high-velocity experiments specifically designed to examine the fragmentation of the projectile during impact. High-strength, well-characterized steel spheres (6.35 mm diameter) were launched with a two-stage light-gas gun to velocities in the range of 3 to 5 km/s. Normal impact with PMMA plates, thicknesses of 0.6 to 11 mm, applied impulsive loads of various amplitudes and durations to the steel sphere. The extent of fragmentation, loss in momentum, and divergence of the debris are shown to correspond to the impact conditions. Multiple flash radiography was used to monitor material motion and fragmentation of the steel sphere during the impact event. Dynamic fragmentation theories, based on energy-balance principles, were used to evaluate local material deformation and fracture state information from CTH, a three-dimensional Eulerian solid dynamics shock wave propagation code. The local fragment characterization of the material defines a weighted fragment size distribution, and the sum of these distributions provides a composite particle size distribution for the steel sphere. The calculated axial and radial velocity changes agree well with experimental data, and the calculated fragment sizes for a specific experiment are in qualitative agreement with the radiographic data.     

Protein-energy malnutrition and oxidative injury in growing rats

1. Weaning rats were fed ad libitum isocaloric diets containing 5% and 20% casein based proteins. 5% protein diet was protein deficient diet. Pair fed rats with the 5% protein group were maintained simultaneously on 20% protein diet but the amount restricted to the amount taken up by PEM group. 2. Glutathione, antioxidative enzymes, lipid peroxidation and histopathological studies in liver and only glutathione and antioxidative enzymes in blood were carried out. 3. Rats fed the 5% protein diet developed a severe protein energy malnutrition (PEM) whereas those on pair-fed diet developed mild to moderate PEM. 4. Glutathione related thiols superoxide dismutase, glutathione peroxidase, catalase and glutathione-Stransferase with (1 Chloro 2,4-dinitro benzene (CDNB) substrate) were decreased in liver with concomitant increase of lipid peroxidation in severe PEM. In blood glutathione, glutathione peroxidase and catalase were decreased while superoxide dismutase was increased in severe PEM group. 5. Mild to moderate PEM (pair-fed group) also resulted in similar changes in liver except glutathione peroxidase, lipid peroxidation in liver and superoxide dismutase in blood. 6. Hepatic injury was detectable only in the severe PEM group. 7. Oxidative-stress and hepatic injury occurred in severe PEM and to a lesser degree in mild to moderate PEM.     

Rapid infusion system for neurosurgical treatment of massive intraoperative hemorrhage

Using an illustrative case of severe closed head injury that resulted in a posterior fossa epidural hematoma (EDH) and supratentorial epidural/subdural hematomas (SDH), the massive blood losses associated with operative repair of the torn sigmoid sinus and the significant fluid losses associated with refractory diabetes insipidus were treated by the intraoperative use of the Rapid Infusion System (RIS, Haemonetics). The RIS can rapidly infuse warm blood, crystalloid, or colloid at rates up to 1.5 L/min, thereby limiting the commonly associated hypotension, hypothermia, and coagulopathies. During the suboccipital craniectomy for evacuation of the EDH and repair of the sigmoid sinus, the patient required 18 units of blood replacement secondary to a large tear in the sigmoid sinus. During a separate craniotomy for evacuation of the SDH, the patient also developed diabetes insipidus, which increased the operative fluid replacement to 39 L. Despite these massive blood and fluid losses, the RIS limited the hypotension to less than 2 min and prevented hypothermia and the frequently associated coagulopathies. When used in a neurosurgical setting associated with massive blood and/or fluid losses, the RIS accomplishes three important objectives: (1) rapid infusion of intravenous fluids for maintaining perfusion pressure, (2) rapid warming of fluids despite high intravenous infusion rates of cold crystalloids, thereby preventing intraoperative hypothermia, and (3) continuous monitoring of infusion rates and totals.     

Multiplexed biochemical assays with biological chips

High density peptide and oligonucleotide chips are fabricated using semiconductor-based technologies. These chips have a variety of biological applications.     

Anabaena sp. strain PCC 7120 responds to nitrogen deprivation with a cascade-like sequence of transcriptional activations

Anabaena sp. strain PCC 7120 adapts to deprivation of fixed nitrogen by undergoing physiological and genetic changes that include formation of N2-fixing heterocysts. Whether or not certain of the genes involved are interdependently expressed has been studied.