Evaluation of hot hardness and creep of a 350 grade commercial maraging steel

The hardening response and the indentation creep of a 350 grade commercial maraging steel were evaluated using a hot hardness tester. The hardness versus temperature plot exhibited three distinct regions. Hardness response was noted between 500–800 K. The unusually high values of activation energy and stress exponent obtained during the creep experiment could be rationalized by a novel concept of introducing a back stress term in the indentation creep relation. The corrected value of the activation energy was found to be reasonably in agreement with the activation energy for diffusion of Ni in iron. Results are supplemented with microstructural observation.     

Using two factor structures of the Mental Adjustment to Cancer (MAC) scale for assessing adaptation to breast cancer

The validity and reliability of two factor structures of the Mental Adjustment to Cancer (MAC) scale for assessing coping style was assessed by examining the relationship between the subscales, psychological distress, and quality of life (QOL) among Stage II and Stage IV breast cancer patients in four phases. First, MANOVAs assessed differences in coping, distress, and QOL across disease stages. Second, for each MAC factor structure, canonical correlation analyses assessed the relationship between coping styles, distress, and QOL, for each disease-stage group separately. Third, structural equation modeling (SEM) assessed the relationship among coping styles, distress, and QOL for all participants. Finally, the internal consistency of both MAC factor structures was assessed using Chronbach's alpha. The results were as follows: (1) significant differences across disease stages were found for coping styles using either the Watson or the Schwartz MAC subscales, but there were no differences in levels of distress or QOL; (2) for both MAC factor structures, coping style was found to be highly related to emotional distress and QOL, however, the strengths of the correlations between individual coping styles and distress/QOL indicators varied across disease stages; (3) SEM indicated that coping style was significantly related to distress and QOL when stage of disease was not considered, and that coping style and indicators of distress/QOL are separate, but highly correlated factors, as opposed to a single latent construct; and, (4) the Watson MAC subscales showed slightly better internal consistency than the Schwartz MAC subscales. Taken together, these findings highlight: (i) the validity of both MAC factor structures for clinical and research use with American breast cancer patients; (ii) the role of coping style as a mediator between disease stage and psychological distress and QOL; and, (iii) the need for refinement of certain Watson and Schwartz subscales.     

A Novel Band-Reject Element for Pseudoelliptic Bandstop Filters

A novel band-reject element for the design of inline waveguide pseudoelliptic band-reject filters is introduced. The element consists of an offset partial-height post in a rectangular waveguide in which the dominant TE₁₀ mode is propagating. The location of the attenuation pole is primarily determined by the height of the post that generates it. The element allows the implementation of weak, as well as strong coupling coefficients that are encountered in asymmetric band-reject responses with broad stopbands. The coupling strength is controlled by the offset of the post with respect to the center of the main waveguide. The posts are separated by uniform sections of the main waveguide. An equivalent low-pass circuit based on the extracted pole technique is first used in a preliminary design. An improved equivalent low-pass circuit that includes a more accurate equivalent circuit of the band-reject element is then introduced. A synthesis method of the enhanced network is also presented. Filters based on the introduced element are designed, fabricated, and tested. Good agreement between measured and simulated results is achieved     

Near-field optical imaging of unstained bacteria: comparison with normal atomic force and far-field optical microscopy in air and aqueous media

Simultaneous near-field scanning optical and atomic force imaging of bacteria is presented. The bacteria imaged in these studies were unstained. The near-field optical images had excellent signal-to-noise and showed excellent contrast even in these unstained specimens. The images obtained were interpreted in terms of the images that have been obtained by transmission electron microscopy and X-ray imaging. The results show that bacterial near-field optical imaging is going to be a very important tool in the arsenal of the bacteriologist both in terms of understanding the fundamental processes in the life cycle of bacteria with and without cytochemical staining and in terms of clinical diagnostic applications.     

High-breakdown-voltage AlInAs/GaInAs junction-modulated HEMT's(JHEMT's) with regrown ohmic contacts by MOCVD

A technology for increasing both the two-terminal gate-drain breakdown and subsequently the three-terminal-off-state breakdown of AlInAs/GaInAs high-electron-mobility transistors (HEMTs) to record values without substantial impact on other parameters is presented. The breakdown in these structures is dependent on the multiplication of electrons injected from the source (channel current) and the gate (gate leakage) into the channel. In addition, holes are generated by high fields at the drain and are injected back into the gate and source electrodes. These phenomena can be suppressed by increasing the gate barrier height and alleviating the fields at the drain. Both have been achieved by incorporating a p⁺-2DEG junction as the gate that modulates the 2DEG gas and by utilizing selective regrowth of the source and drain regions by MOCVD. The 1-μm-gate-length devices fabricated have two-terminal gate-drain and three-terminal-off-state breakdown voltages of 31 V and 28 V, respectively     

Mycoplasma hyorhinis infection of pigs selectively bred for high and low immune response

Fourier transform infrared microspectroscopy (FTIR) was used to study glasses of pure carbohydrates and in the cytoplasm of desiccation tolerant plant organs. The position of the OH stretching vibration band (vOH) shifted with temperature. Two linear regression lines were observed in vOH against temperature plots. The temperature at the point of intersection between these two lines coincided with the glass transition temperature (Tg), as determined by other methods. The temperature at the intersection point decreased with increasing water content, which further validates that, indeed, Tg was observed. Tg values that were determined for dry glucose, sucrose, maltose, trehalose and raffinose glasses were 27, 57, 91, 108 and 108 degrees C, respectively. The shift of vOH with temperature, the wavenumber-temperature coefficient (WTC), was higher in sugar glasses having higher Tg. This suggests that glasses are more loosely packed when they have higher Tg. For Typha latifolia pollen and dried Craterostigma plantagineum leaves we obtained similar vOH vs. temperature plots as for carbohydrate glasses, indicating that a glass transition was observed. The Tg in dry pollen was ca. 45 degrees C and in dry plant leaves ca. 65 degrees C, with WTC values comparable to those observed in the carbohydrates. The Tg values in these tissues decreased with increasing water contents. Our data suggest that the carbohydrates that are present in the cytoplasm are primary factors contributing to the glassy state. We conclude that FTIR provides new insights in the structure of glasses in carbohydrates and in biological tissues.     

Ion microbeam radiation system

An ion microbeam radiation test system has been built for studying radiation-induced charge collection and single event upsets in advanced semiconductor circuits. With this system, it is possible to direct an ion beam of a diameter as small as 1 μm onto a circuit or test structure with a placement accuracy of 1 μm. The components of the system and its operation are described. Applications are described which demonstrate the capabilities of the system