Analysis of STS-3 Get Away Special (GAS) flight data and vibration specification for gas payloads

During the Space Transportation System (STS)-3 mission, a Get Away Special (GAS) canister was flown. In order to determine the flight environment for GAS payloads, triaxial accelerometers and a microphone were installed inside the GAS canister. Data from these accelerometers and the microphone were analyzed. The microphone data is presented as overall sound pressure level (SPL) and one-third octave band time history plots. And the accelerometer data is provided in the forms of instantaneous time history, RMS time history and power spectral density plots. Also based on this flight data, vibration test specification for GAS payloads was developed and the recommended specification is presented here

Evaluation of mounting bolt loads for Space Shuttle Get Away Special (GAS) adapter beam

During the prototype vibration tests of the GAS adapter beam, significant impacting of the beam at its support points was observed. The cause of the impacting was traced to gaps under the mounting bolt heads. Because of the nonlinear nature of the response, it was difficult to evaluate the effects which Shuttle launch dynamics might have on the mounting bolt loads. A series of tests were conducted on an electrodynamic exciter in which the transient acceleration time histories, which had been measured during the Space Transportation System-1 (STS-1; Space Shuttle mission 1) launch, were simulated. The actual flight data had to be filtered and compensated so that it could be reproduced on the shaker without exceeding displacement and velocity limitations. Mounting bolt loads were measured directly by strain gages applied to the bolts. Various gap thicknesses and bolt torques were investigated. Although increased gap thickness resulted in greater accelerations due to impacting, the bolt loads were not significantly affected. This is attributed to the fact that impacting excited mostly higher frequency modes which do not have significant modal mass

Intrinsic carrier mobility of multi-layered MoS2_2 field-effect transistors on SiO2_2

By fabricating and characterizing multi-layered MoS$_2$-based field-effect transistors (FETs) in a four terminal configuration, we demonstrate that the two terminal-configurations tend to underestimate the carrier mobility $\mu$ due to the Schottky barriers at the contacts. For a back-gated two-terminal configuration we observe mobilities as high as 125 cm$^2$V$^{-1}$s$^{-1}$ which is considerably smaller than 306.5 cm$^2$V$^{-1}$s$^{-1}$ as extracted from the same device when using a four-terminal configuration. This indicates that the intrinsic mobility of MoS$_2$ on SiO$_2$ is significantly larger than the values previously reported, and provides a quantitative method to evaluate the charge transport through the contacts.Comment: 8 pages, 5 figures, typos fixed, and references update

Proton-induced magnetic order in carbon: SQUID measurements

In this work we have studied systematically the changes in the magnetic behavior of highly oriented pyrolytic graphite (HOPG) samples after proton irradiation in the MeV energy range. Superconducting quantum interferometer device (SQUID) results obtained from samples with thousands of localized spots of micrometer size as well on samples irradiated with a broad beam confirm previously reported results. Both, the para- and ferromagnetic contributions depend strongly on the irradiation details. The results indicate that the magnetic moment at saturation of spots of micrometer size is of the order of $10^{-10}$ emu.Comment: Invited contribution at ICACS2006 to be published in Nucl. Instr. and Meth. B. 8 pages and 6 figure

Growth of carbon nanotubes on quasicrystalline alloys

We report on the synthesis of carbon nanotubes on quasicrystalline alloys. Aligned multiwalled carbon nanotubes (MWNTs) on the conducting faces of decagonal quasicrystals were synthesized using floating catalyst chemical vapor deposition. The alignment of the nanotubes was found perpendicular to the decagonal faces of the quasicrystals. A comparison between the growth and tube quality has also been made between tubes grown on various quasicrystalline and SiO2 substrates. While a significant MWNT growth was observed on decagonal quasicrystalline substrate, there was no significant growth observed on icosahedral quasicrystalline substrate. Raman spectroscopy and high resolution transmission electron microscopy (HRTEM) results show high crystalline nature of the nanotubes. Presence of continuous iron filled core in the nanotubes grown on these substrates was also observed, which is typically not seen in MWNTs grown using similar process on silicon and/or silicon dioxide substrates. The study has important implications for understanding the growth mechanism of MWNTs on conducting substrates which have potential applications as heat sinks

Total body irradiation in a case of thalassemia major with source to axis distance based planning: A case report

Background: The use of total body radiation (TBI) before hematopoietic stem cell transplantation (HSCT) would increase the engraftment without transplant-related morbidity or mortality among Thalassemia major (TM) cases. Case presentation: A 2-year-old female child, diagnosed with TM was scheduled for haploidentical allogenic transplant-based protocol, and after that, based on protocol she was scheduled to undergo a single session of TBI as a conditioning regimen before haploidentical allogenic hematopoietic stem cell tranplant. A total dose of 4 Gy was administered.. The incidence of graft failure was reduced as TBI was used before allogeneic stem cell transplantation. TBI provided a uniform dose of radiation to the entire body, penetrating areas such as the central nervous system (CNS) and testes. Conclusion: Total Body Irradiation with the SAD technique is the most effective way of treatment. As it is comfortable for the patient to undergo, easily reproducible, and it helps to achieve a uniform dose distribution

Total body irradiation in a case of thalassemia major with source to axis distance based planning: A case report

Background: The use of total body radiation (TBI) before hematopoietic stem cell transplantation (HSCT) would increase the engraftment without transplant-related morbidity or mortality among Thalassemia major (TM) cases. Case presentation: A 2-year-old female child, diagnosed with TM was scheduled for haploidentical allogenic transplant-based protocol, and after that, based on protocol she was scheduled to undergo a single session of TBI as a conditioning regimen before haploidentical allogenic hematopoietic stem cell tranplant. A total dose of 4 Gy was administered.. The incidence of graft failure was reduced as TBI was used before allogeneic stem cell transplantation. TBI provided a uniform dose of radiation to the entire body, penetrating areas such as the central nervous system (CNS) and testes. Conclusion: Total Body Irradiation with the SAD technique is the most effective way of treatment. As it is comfortable for the patient to undergo, easily reproducible, and it helps to achieve a uniform dose distribution