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T-shape, LPCVD silicon nitride cantilevers are fabricated to determine Young's modulus and fracture strength of silicon nitride thin films at room and cryogenic temperatures. A helium-cooled measurement setup is developed and installed inside a focused-ion-beam (FIB) system. A lead-zirconate-titanate (PZT) translator powered by a function generator and a dc voltage is utilized as an actuator, and a silicon diode is used as a temperature sensor in this setup. Resonant frequencies of identical cantilevers with different "milling masses" are measured to obtain thickness and Young's modulus of the silicon nitride thin films, while a bending test is performed to obtain fracture strength. From the experiment, the average Young's modulus of low-pressure chemical-vapor deposition (LPCVD) silicon nitride thin films varies from 260.5 GPa at room temperature (298 K) to 266.6 GPa at 30 K, and the average fracture strength ranges from 6.9 GPa at room temperature to 7.9 GPa at 30 K. The measurement setup and technique presented here can be used to characterize the mechanical properties of different MEMS materials at cryogenic temperatures.

Mechanical properties of micro-electro-mechanical systems (MEMS) materials at cryogenic temperatures are investigated to extend MEMS devices into space applications. A helium-cooled measurement setup mimicking the outer space environment is developed and installed inside a focused-ion-beam (FIB) system. T-shape, low-stress LPCVD silicon nitride cantilevers suspended on a silicon substrate are fabricated as the test structures using bulk micromachining technique. A lead-zirconate-titanate (PZT) translator and a silicon diode are utilized as an actuator and a temperature sensor in the measurement setup, respectively. The resonant frequencies of an identical cantilever with different “milling masses” are measured to obtain the thickness and the Young's modulus. Additionally, a bending test is performed to determine the fracture strength. From the experiments, the Young's modulus of LPCVD silicon nitride thin films varies from 260.5 GPa ± 5.4 GPa at room temperature (298 K) to 266.6 GPa ± 4.1 GPa at 30 K, while the fracture strength ranges from 6.9 GPa ± 0.6 GPa at room temperature to 7.9 GPa ± 0.7 GPa at 30 K.

In the present study, we have investigated the pro-opiomelanocortin (POMC)-derived neuropeptide alpha-MSH for its ability to modulate activation of human mast cells. The in vitro ability of purified human skin mast cells to secrete various types of mast cell mediators was monitored in response to alpha-MSH at the mRNA and at the protein level. Picomolar concentrations of alpha-MSH induced a dose-dependent release of histamine from isolated human skin mast cells and from skin punch biopsies. However, no effect of alpha-MSH was seen regarding the expression of IL-1, IL-6, IL-8, TGF-beta, and TNF-alpha. Melanocortin receptor MC-1 was identified at the transcriptional level by RT-PCR analysis but not at the protein level, whereas, in leukemic human mast cells (HMC-1), the mRNAs and the proteins for the MC-1 and MC-5 receptor were identified. These results suggest that alpha-MSH may selectively induce acute inflammatory effects via secretion of histamine.

We present a cryogenic measurement setup installed inside a focused-ion-beam (FIB) system to characterize and microrepair microelectromechanical systems (MEMS) for space applications. The setup allows testing of MEMS devices under vacuum condition of 10−6Torr at variable temperatures ranging from 298to20K. In the experiment, a lead-zirconate-titanate translator powered by a function generator and a dc voltage is utilized as an actuator, and a thin-film thermo-resistor fabricated with test devices is used as an integrated temperature sensor. Additionally, a motorized x-y-z stage is installed to achieve highly accurate positioning function. Resonant techniques and bending tests based on the designed setup are developed to measure the mechanical properties of silicon nitride thin films at cryogenic temperatures. Combined with the functions of the FIB system, this setup also demonstrates the capability to microrepair microshutter arrays, programmable field selectors in the NASA James Webb Space Telescopes. Th...

Serum lysozyme has been demonstrated to be an indicator for macrophage activity in the tumor-bearing host. Therefore, we investigated lysozyme levels in the sera of 336 untreated tumor patients (121 malignant melanoma, 61 lung cancers, 70 cervical cancers, 49 breast cancers and 35 benign breast tumors, and 36 healthy controls). Patients with malignant melanoma and lung cancer had significantly higher lysozyme levels than the healthy controls. Within the clinical stages in melanoma, there was a decrease of lysozyme in stages II and III in comparison to stage I, but still above that of the control values. Patients with benign breast tumors had normal levels, whereas in breast cancer patients of stages I and II there was a significant reduction in the lysozyme levels. In stages III and IV no differences to the control group could be detected. In patients with cervical cancer (FIGO II and III) serum lysozyme levels were found to be within the normal range. From this study it can not be concluded that serum lysozyme reflects the immunological reactivity of the tumor bearer. Nevertheless, the reduced levels in stages I and II of breast cancer might point to an immunological defect.