Wear mechanisms found in angular contact ball bearings of the SSME's LOX turbopump

Extensive experimental investigations were carried out on used flight bearings of the Phase 2 high-pressure oxygen turbopump (HPOTP) of the Space Shuttle Main Engine (SSME) in order to determine the wear mechanisms, dominant wear modes, and their extent and causes. The report shows methodology, surface analysis techniques used, result, and discussion. The mode largely responsible for heavy bearing wear in LOX was identified as adhesive/shear peeling of the upper layers of bearing balls and rings. The mode relies on the mechanisms of scale formation, breakdown, and removal, all of which are greatly enhanced by the heavy oxidation environment of the HPOTP. Major causes of the high wear in bearings appear to be lubrication and cooling, both inadequate for the imposed conditions of operation. Numerous illustrations and evidence are given

Acute phase protein levels in dogs with mast cell tumours and sarcomas

<p><b>Context:</b> The acute phase protein response is part of a non-specific and complex host response to inflammation. It occurs shortly after tissue injury and may be induced by a range of different causes, including infectious, inflammatory, neoplastic, traumatic or immunological disease. Although it was conventionally believed that APPs were exclusively hepatocyte derived, there is increasing evidence to support extra-hepatic generation in neoplastic and other disease states. In people, C-reactive protein (CRP) has been shown to be of value in identifying metastatic disease from primary renal tumours as well as showing promise for monitoring rejection of renal transplants. Serum CRP correlates with survival in colorectal cancer and oesophageal squamous cell carcinoma while serum amyloid A (SAA) concentrations correlate with cancer activity, stage and prognosis in gastric tumours. Recent immunohistochemical studies in people with oesophageal carcinoma suggest that tumour tissue may itself elaborate APP with a poorer survival and outcome associated with tumours elaborating higher levels of CRP. A similar association has been seen between alpha-1 acid glycoprotein (AGP) and colorectal tumours and ovarian carcinoma.</p> <p>As yet, studies regarding APP values in neoplastic conditions in dogs are limited, and many are non-specific. In veterinary patients, elevated levels of AGP have been identified in dogs with a range of tumours with localisation to liver and splenic tissue in one study. Another study found higher levels of AGP in dogs with non-specific tumours of grade III-IV based on the WHO Tumour Node Metastasis (TNM) scale and elevated serum AGP has been documented in non-specific tumour-bearing cats. Elevated CRP levels have been documented in both dogs and cats with lymphoma and serum CRP may be used as an indicator of complete remission status in dogs with multicentric lymphoma. Elevated levels of CRP, Haptoglobin (Hp) and SAA have been identified in dogs with mammary tumours, with significant increases over normal in the presence of metastatic disease, primary tumours greater than 5cm in diameter and those with ulceration.</p> <p>In this study we evaluated an APP profile using four APPs (CRP, Hp, SAA and AGP), in dogs with mast cell tumours (MCTs) and sarcomas to assess whether the APP profile would change in reflection of tumour presence; whether the extent of any change would correlate with tumour grade; and whether the changes would differ with tumour type.</p> <p><b>Approach:</b> Patients with naturally occurring MCTs and sarcomas presenting for staging and treatment were included if they met the study criteria. Criteria for inclusion were that the patient was not currently being treated with steroids, did not have a recent history of infectious or inflammatory disease other than the tumour, a definitive histological diagnosis was available and a full staging procedure was completed prior to surgery using standard oncological protocols to identify metastatic disease where present. Following surgical resection each tumour was submitted for full histological evaluation and grading to include assessment of the margins of excision. Cases were only enrolled in the study if blood sampling formed part of the clinical investigation and/or treatment, and where residual blood was available after diagnostic sampling which would otherwise have been disposed of as clinical waste. In brief, the CRP levels were determined by immunoturbidometric assay and Hp by means of haemoglobin binding capacity assay. SAA was measured with a commercial canine ELISA kit (TriDelta Development, Dublin, Ireland) and AGP was measured with a commercial radial immunodiffusion assay (J-Path Inc, Tokyo, Japan).</p> <p><b>Results:</b> All comparisons using continuous data were checked for normality and equality of variances and appropriate statistical tests were employed (student’s t test operationalised as a two-sample Welch’s test for samples of unequal sizes and variances, Mann-Whitney, Chi-square and Fishers exact tests as appropriate). In MCTs, the CRP and AGP were elevated above reference ranges, Hp showed no significant change and SAA dropped relative to the reference range. In sarcoma patients CRP, Hp and AGP were all elevated above reference ranges. None of the tumour grade differences were significant apart from SAA in sarcoma patients where values in grade 2 sarcoma were significantly higher than those in grade 1.</p> <p><b>Interpretation and notes of caution:</b> The numbers in our groups were small which compromises the validity of statistical evaluation so our results must be interpreted with caution. However some interesting relationships have emerged from the initial evaluation which suggests that APP profiles may have potential for screening in patients with neoplastic disease. For patients with MCTs, CRP and AGP levels would be expected to increase, with a concurrent drop in SAA levels. In sarcoma patients CRP, AGP and Hp can all be expected to increase. These initial results need to be evaluated in larger numbers of cases with naturally occurring disease to validate the findings, to assess whether the presence and extent of metastatic disease has a significant effect, and also to confirm whether the values alter after surgical resection of the primary tumour.</p> <p><b>Significance of findings:</b> If there are consistent and specific changes in APP profiles associated with different tumour types in dogs, as is the case with a wide range of cancers in humans, then there may be potential for APP profiles on routine blood samples to be used as indicators of disease, or where monitoring for recurrence. Whether they could also have potential for assessment of the presence of metastatic disease and prognosis as in people is unknown as yet.</p&gt

VHF downline communication system for SLAR data

A real time VHF downlink communication system is described for transmitting side-looking airborne radar (SLAR) data directly from an aircraft to a portable ground/shipboard receiving station. Use of this receiving station aboard the U.S. Coast Guard icebreaker Mackinaw for generating real-time photographic quality radar images is discussed. The system was developed and demonstrated in conjunction with the U.S Coast Guard and NOAA National Weather Service as part of the Project Icewarn all weather ice information system for the Great Lakes Winter Navigation Program

InSb charge coupled infrared imaging device: The 20 element linear imager

The design and fabrication of the 8585 InSb charge coupled infrared imaging device (CCIRID) chip are reported. The InSb material characteristics are described along with mask and process modifications. Test results for the 2- and 20-element CCIRID's are discussed, including gate oxide characteristics, charge transfer efficiency, optical mode of operation, and development of the surface potential diagram

Detailed study of oxidation/wear mechanism in lox turbopump bearings

Wear of 440C angular contact ball bearings of the phase 2 high pressure oxygen turbopump (HPOTP) of the space shuttle main engine (SSME) has been studied by means of various advanced nondestructive techniques (NDT) and modeled with reference to all known material, design, and operation variables. Three modes dominating the wear scenario were found to be the adhesive/sheer peeling (ASP), oxidation, and abrasion. Bearing wear was modeled in terms of the three modes. Lacking a comprehensive theory of rolling contact wear to date, each mode is modeled after well-established theories of sliding wear, while sliding velocity and distance are related to microsliding in ball-to-ring contacts. Microsliding, stress, temperature, and other contact variables are evaluated with analytical software packages of SHABERTH(TM)/SINDA(TM) and ADORE(TM). Empirical constants for the models are derived from NIST experiments by applying the models to the NIST wear data. The bearing wear model so established precisely predicts quite well the average ball wear rate for the HPOTP bearings. The wear rate has been statistically determined for the entire population of flight and development bearings based on Rocketdyne records to date. Numerous illustrations are given

Correspondence Estimation from Non-Rigid Motion Information

The DIET (Digital Image Elasto Tomography) system is a novel approach to screen for breast cancer using only optical imaging information of the surface of a vibrating breast. 3D tracking of skin surface motion without the requirement of external markers is desirable. A novel approach to establish point correspondences using pure skin images is presented here. Instead of the intensity, motion is used as the primary feature, which can be extracted using optical flow algorithms. Taking sequences of multiple frames into account, this motion information alone is accurate and unambiguous enough to allow for a 3D reconstruction of the breast surface. Two approaches, direct and probabilistic, for this correspondence estimation are presented here, suitable for different levels of calibration information accuracy. Reconstructions show that the results obtained using these methods are comparable in accuracy to marker-based methods while considerably increasing resolution. The presented method has high potential in optical tissue deformation and motion sensing

Vacuum-UV negative photoion spectroscopy of CF3Cl, CF3Br and CF3I

Using synchrotron radiation negative ions have been detected by mass spectrometry following vacuum-UV photoexcitation of trifluorochloromethane (CF$_3$Cl), trifluorobromomethane (CF$_3$Br) and trifluoroiodomethane (CF$_3$I). The anions F$^-$, X$^-$, F$_2^-$, FX$^-$, CF$^-$, CF$_2^-$ and CF$_3^-$ were observed from all three molecules, where X = Cl, Br or I, and their ion yields recorded in the range 8-35 eV. With the exception of Br$^-$ and I$^-$, the anions observed show a linear dependence of signal with pressure, showing that they arise from unimolecular ion-pair dissociation. Dissociative electron attachment, following photoionization of CF$_3$Br and CF$_3$I as the source of low-energy electrons, is shown to dominate the observed Br$^-$ and I$^-$ signals, respectively. Cross sections for ion-pair formation are put on to an absolute scale by calibrating the signal strengths with those of F$^-$ from both SF$_6$ and CF$_4$. These anion cross sections are normalized to vacuum-UV absorption cross sections, where available, and the resulting quantum yields are reported. Anion appearance energies are used to calculate upper limits to 298 K bond dissociation energies for $D^0$(CF$_3$-X) which are consistent with literature values. We report new data for $D^0$(CF$_2$I$^-$-F) ≤ 2.7 ± 0.2 eV and $\Delta_fH^0_{298}$ (CF$_2$I$^+$) ≤ (598 ± 22) kJ mol$^{-1}$. No ion-pair formation is observed below the ionization energy of the parent molecule for CF$_3$Cl and CF$_3$Br, and only weak signals (in both I$^-$ and F$^-$) are detected for CF$_3$I. These observations suggest neutral photodissociation is the dominant exit channel to Rydberg state photoexcitation at these lower energies

Adapting to the digital age: a narrative approach

The article adopts a narrative inquiry approach to foreground informal learning and exposes a collection of stories from tutors about how they adapted comfortably to the digital age. We were concerned that despite substantial evidence that bringing about changes in pedagogic practices can be difficult, there is a gap in convincing approaches to help in this respect. In this context, this project takes a “bottom-up” approach and synthesises several life-stories into a single persuasive narrative to support the process of adapting to digital change. The project foregrounds the small, every-day motivating moments, cultural features and environmental factors in people's diverse lives which may have contributed to their positive dispositions towards change in relation to technology enhanced learning. We expect that such narrative approaches could serve to support colleagues in other institutions to warm up to ever-changing technological advances

Stacking order dynamic in the quasi-two-dimensional dichalcogenide 1T-TaS2_2 probed with MeV ultrafast electron diffraction

Transitions between different charge density wave (CDW) states in quasi-two-dimensional materials may be accompanied also by changes in the inter-layer stacking of the CDW. Using MeV ultrafast electron diffraction, the out-of-plane stacking order dynamics in the quasi-two-dimensional dichalcogenide 1T-TaS$_2$ is investigated for the first time. From the intensity of the CDW satellites aligned around the commensurate $l$ = 1/6 characteristic stacking order, it is found out that this phase disappears with a 0.5 ps time constant. Simultaneously, in the same experiment, the emergence of the incommensurate phase, with a slightly slower 2.0 ps time constant, is determined from the intensity of the CDW satellites aligned around the incommensurate $l$ = 1/3 characteristic stacking order. These results might be of relevance in understanding the metallic character of the laser-induced metastable "hidden" state recently discovered in this compound

Report of the panel on lithospheric structure and evolution, section 3

The panel concluded that NASA can contribute to developing a refined understanding of the compositional, structural, and thermal differences between continental and oceanic lithosphere through a vigorous program in solid Earth science with the following objectives: determine the most fundamental geophysical property of the planet; determine the global gravity field to an accuracy of a few milliGals at wavelengths of 100 km or less; determine the global lithospheric magnetic field to a few nanoTeslas at a wavelength of 100 km; determine how the lithosphere has evolved to its present state via acquiring geologic remote sensing data over all the continents