Study of portal hypertension in children with special reference to sclerotherapy

Spinal cord injuries are rare in children, in face of their higher mobility comparing to adults. The high cervical and the thoracic segments of the spine are more frequently affected. In the last 10 years we had 90 cases of spinal injuries in our service being 12 with neurologic deficient (8 male and 4 female) and four of them without radiographic abnormality, even in the dynamics studies. The authors emphasise the possibility of occurrence of neurologic deficit in children after trauma, even without any radiographic abnormality.     

Interleukin-2-activated hematopoietic stem cell transplantation for breast cancer: investigation of dose level with clinical correlates

Incubating hematopoietic stem cells with IL-2 in vitro for 24 h generates cytotoxic T cells. When infused into patients, these cells may stimulate a graft-versus-tumor (GVT) effect. This clinical trial was designed to assess the ability of IL-2 activated peripheral blood stem cells (PBSC) to reconstitute hematopoiesis, to investigate dose levels and dose-limiting toxicities of IL-2, and to evaluate clinical results and preliminary laboratory effects using a combination of IL-2-activated autologous PBSC followed by IL-2 after transplantation. Sixty-one women with stage II-IV breast cancer were treated. After the administration of carboplatin (200 mg/m2/day for 3 days) and cyclophosphamide (2 g/m2/day for 3 days), patients received autologous PBSC that were cultured in IL-2 for 24 h followed by parenteral administration of IL-2 beginning the day of transplantation. Three escalating doses of IL-2 were evaluated with increasing duration up to 4 weeks. Of the 57 patients receiving IL-2 after tranplantation, 19 patients (33.3%) were unable to complete the planned course of IL-2 therapy due to persistent fevers (n = 9), diarrhea (n = 2), pulmonary capillary leak syndrome (n = 3), development of a rash (n = 1), atrial fibrillation (n = 1), or patient's request (n = 3). One death occurred during hospitalization. Engraftment of neutrophils occurred on day 11.5 (mean; range 8-21 days) and platelets on day 11.7 (mean; range 7-33 days). The maximal tolerated dose of IL-2 was 6 x 10(5) IU/m2/day for 4 weeks. Disease-free survival rates for all stages were comparable to current reports in the literature. Preliminary laboratory evaluations include FACScan analysis of the IL-2 activated PBSC demonstrating an increased percentage of CD3+, CD25+, HLA-DR+ T cells. Phenotypically similar cells were present in peripheral blood samples of patients when tested 15 days after transplantation. This study demonstrates successful engraftment with IL-2-activated PBSC after high-dose chemotherapy for women with stage II-IV breast cancer. The regimen is feasible and, although toxicities are common, they are manageable and correlate with increasing dose and duration of IL-2.     

TRANSFER EFFICIENCY ENHANCEMENT OF POWER COATING APPLICATION USING RESPONSE SURFACE METHODOLOGY

Due to low content of volatile organic compounds and the ability to reclaim unused material, powder coatings present an environmentally friendly and economical means of providing protective and decorative finishes. Because the ratio of reclaimable material to virgin powder is kept low in many applications, obtaining high first pass transfer efficiency (FPTE) is a topic of current research. Theoretical models necessary to determine optimum operating conditions are very complex due to interactions of multiple parameters that determine FPTE. Frequently, a simplified approach is desirable to obtain solutions for optimization. Empirical methods can be used which can provide adequate tools for optimization in a short time. This paper describes response surface methodology and applies it to enhance the relative first pass transfer efficiency of an industrial powder coating process.     

Microstructure and wear properties

The laser surface cladding technique was used to formin situ Fe-Cr-Mn-C alloys on AISI 1016 steel substrate. In this process mixed powders containing Cr, Mn, and C with a ratio of 10:1:1 were delivered using a screw feed, gravity flow carrier gas aided system into the melt pool generated by a 10 kw CO₂ laser. This technique produced ultrafine microstructure in the clad alloy. The microstructure of the laser surface clad region was investigated by optical, scanning, and transmission electron microscopy and X-ray microanalysis techniques. Microstructural study showed a high degree of grain refinement and an increase in solid solubility of alloying elements which, in turn, produced a fine distribution of complex types of carbide precipitates in the ferrite matrix because of the high cooling rate. An alloy of this composition does not show any martensitic or retained austenite phase. In preliminary wear studies the laser clad Fe-Cr-Mn-C alloys exhibited far superior wear properties compared to Stellite 6 during block-on-cylinder tests. The improved wear resistance is attributed to the fine distribution of metastable M₆C carbides.     

Non-equilibrium synthesis of Fe-Cr-C-W alloy by laser cladding

Synthesis of Fe-Cr-C-W alloy using the laser cladding technique offered an opportunity to produce a novel wear-resistant material with fine and uniform microstructure. Use of preheating during laser cladding Fe-Cr-C-W provided crack-free clads. The preheating temperature was very critical to eliminate cracks in the clad. Different complex types of carbide were observed in this research. Overall laser process parameters such as power density or specific energy as well as preheating temperature affected the characteristics of the carbide precipitates in the matrix. The increase of solid solubility and high cooling rate resulted in good metallurgical characteristics. Mostly M₆C or M₂₃C₆ type carbides were observed. Usually diamond-shaped M₆C carbides showed good tribological characteristics. In general, increasing the power density brought an increase of average hardness, while decreasing the power density brought a decrease of wear scar width. The laser-clad Fe-Cr-C-W alloy showed better wear properties than laser-clad Fe-Cr-Mn-C and several times smaller scar width as compared to Stellite 6 hard-facing during line-contact wear testing.     

Technology and layout-related testing of static random-access memories

Static random-access memories (SRAMs) exhibit faults that are electrical in nature. Functional and electrical testing are performed to diagnose faulty operation. These tests are usually designed from simple fault models that describe the chip interface behavior without a thorough analysis of the chip layout and technology. However, there are certaintechnology and layout-related defects that are internal to the chip and are mostly time-dependent in nature. The resulting failures may or may not seriously degrade the input/output interface behavior. They may show up as electrical faults (such as a slow access fault) and/or functional faults (such as a pattern sensitive fault). However, these faults cannot be described properly with the functional fault models because these models do not take timing into account. Also, electrical fault models that describe merely the input/output interface behavior are inadequate to characterize every possible defect in the basic SRAM cell. Examples of faults produced by these defects are: (a) static data loss, (b) abnormally high currents drawn from the power supply, etc. Generating tests for such faults often requires a thorough understanding and analysis of the circuit technology and layout. In this article, we shall examine ways to characterize and test such faults. We shall divide such faults into two categories depending on the types of SRAMs they effect—silicon SRAMs and GaAs SRAMs.     

Viscous and Joulean power losses in liquid-metal sliding electricalcontacts with finite electrically conducting electrodes

Designing high performance liquid-metal sliding electrical contacts for homopolar machinery requires a precise knowledge of the magnitudes of the viscous and Joulean losses under various operating conditions. The liquid metal, which is confined to a channel between a rotor and stator, is subjected to a large external magnetic induction while transporting current. Significant power losses can occur in these devices. The geometry and electrical conductivity of the channel walls have a significant effect on these losses. In past theoretical work, copper electrodes were generally treated as perfect electrical conductors as compared to liquid metals. Calculations based on this perfectly conducting electrode approximation predicted unrealistically high power losses. In the present study, the effects of electrodes with finite conductivity on both the viscous dissipation and Joulean heating are explored. Numerical results are presented for both radial and axial magnetic inductions. It is found that the magnetic induction orientation has a significant impact on the losses. The results of this type of analysis can be used to minimize the power losses in the design of liquid-metal sliding electrical contacts     

Processing,microstructure, and properties of laser-clad Ni alloy FP-5 on Al alloy AA333

This article describes the results of laser cladding Ni alloy FP-5 on Al alloy AA333, microstructure and crystal structure characterization, and properties of the clad evaluated by Vickers hardness measurement and wear testing. Direct cladding of Ni alloy on Al alloy creates brittle Ni _x Al _y compounds in the interface, which make the interface very brittle, and result in cracking at the interface. The compound formation is avoided by introducing an intermediate layer of Cu or bronze. The cracking tendency of the clad is prevented by preheating the substrate to 673 K. The microstructure and crystal structure of the clad and interface are investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Five phases in the clad layer (including three new phases) and two phases in the interface are identified by convergent beam electron diffraction (CBED) and selected area diffraction (SAD) studies. The mechanical properties of the laser-clad Ni alloy are evaluated by Vickers hardness measurements and wear testing, which show superior results over Cu- and Fe-based alloys.     

Effects of surface properties on the tribocharging characteristics of polymer powder as applied to industrial processes

Experiments performed on different powders of different size distributions tribocharged with stainless-steel (SS) beads showed the charge acquired by the powder could be correlated with the actual work function difference between the powder and SS. Ultraviolet and X-ray photoelectron spectroscopy were performed on various materials involved, and showed the work function increased with surface contamination and oxidation, and the difference narrowed for metals and polymers. Such a small difference in work function may contribute to bipolar charging. Experiment data showed that while charge acquired increased with particle size, the charge distribution was generally bipolar. Both surface analysis and charge distribution studies suggest that for tribocharging, minimization of oxidation and surface contamination are needed. It also appears that the relative humidity must also be controlled to obtain reliable tribocharging. Semiempirical molecular modeling calculations of the work function of several polymers showed good agreement with experiment. Surface plasma treatment is presented as a viable method for modifying the work function.