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  • Aerospace Medicine  (7)
  • Chemical Engineering
  • FLUID MECHANICS AND HEAT TRANSFER
  • 2005-2009  (7)
  • 1990-1994
  • 1970-1974
  • 1960-1964  (1)
  • 2005  (7)
  • 1961  (1)
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  • 2005-2009  (7)
  • 1990-1994
  • 1970-1974
  • 1960-1964  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 7 (1961), S. 72-77 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The mixing efficiency of simple and pitched paddles, marine propellers, and centrifugal and disk impellers was determined by a heat transfer method in a single stage of a large pump-mix mixer-settler. The mixing devices were from 3 to 5 in. in diameter and were tested with a refined kerosene as the organic phase and water as the aqueous phase.A heat conductance was calculated from flow parameters and the efficiency and was correlated against impeller design and speed variables. For centrifugal and disk impellers UA was proportional to n1.2L3b0.3; for the paddles UA was proportional to n1.67L2.5b0.42. At normal operating speeds controlled variation of the internal recirculation of mixed phases through a centrifugal impeller did not change the efficiency.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2011-08-24
    Description: High-protein and acidogenic diets induce hypercalciuria. Foods or supplements with excess sulfur-containing amino acids increase endogenous sulfuric acid production and therefore have the potential to increase calcium excretion and alter bone metabolism. In this study, effects of an amino acid/carbohydrate supplement on bone resorption were examined during bed rest. Thirteen subjects were divided at random into two groups: a control group (Con, n = 6) and an amino acid-supplemented group (AA, n = 7) who consumed an extra 49.5 g essential amino acids and 90 g carbohydrate per day for 28 days. Urine was collected for n-telopeptide (NTX), deoxypyridinoline (DPD), calcium, and pH determinations. Bone mineral content was determined and potential renal acid load was calculated. Bone-specific alkaline phosphatase was measured in serum samples collected on day 1 (immediately before bed rest) and on day 28. Potential renal acid load was higher in the AA group than in the Con group during bed rest (P 〈 0.05). For all subjects, during bed rest urinary NTX and DPD concentrations were greater than pre-bed rest levels (P 〈 0.05). Urinary NTX and DPD tended to be higher in the AA group (P = 0.073 and P = 0.056, respectively). During bed rest, urinary calcium was greater than baseline levels (P 〈 0.05) in the AA group but not the Con group. Total bone mineral content was lower after bed rest than before bed rest in the AA group but not the Con group (P 〈 0.05). During bed rest, urinary pH decreased (P 〈 0.05), and it was lower in the AA group than the Con group. These data suggest that bone resorption increased, without changes in bone formation, in the AA group.
    Keywords: Aerospace Medicine
    Type: Journal of applied physiology (Bethesda, Md. : 1985) (ISSN 8750-7587); Volume 99; 1; 134-40
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  • 3
    Publication Date: 2011-08-24
    Description: No abstract available
    Keywords: Aerospace Medicine
    Type: Gravitational and space biology bulletin : publication of the American Society for Gravitational and Space Biology (ISSN 1089-988X); Volume 18; 2; 111-2
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  • 4
    Publication Date: 2019-07-18
    Description: Defining optimal nutrient requirements is imperative to ensure crew health on long-duration space exploration missions. To date, nutrient requirement data have been extremely limited because of small sample sizes and difficulties associated with collecting biological samples. In this study, we examined changes in body composition, bone metabolism, hematology, general blood chemistry, and blood levels of selected vitamins and minerals after long-duration (128-195 d) space flight aboard the International Space Station. Crew members consumed an average of 80% of the recommended energy intakes, and on landing day their body weight had decreased (P=0.051). After flight, hematocrit was less, and serum femtin was greater than before flight (P〈0.01). Serum iron, ferritin saturation, and transferrin had decreased after flight. The finding that other acute-phase proteins, including ceruloplasmin, retinol binding protein, transthyretin, and albumin were not changed after flight suggests that the changes in iron metabolism may not be strictly due to an inflammatory response. Urinary 8- hydroxy-2'-deoxyguanosine concentration was greater and superoxide dismutase was less after flight, indicating that oxidative damage had increased (P〈0.05). Despite the reported use of vitamin D supplements during flight, serum 25-hydroxyvitamin D was significantly decreased after flight (P〈0.01). Bone resorption was increased after flight, as indicated by several urinary markers of bone resorption. Bone formation, assessed by serum concentration of bone-specific alkaline phosphatase, was elevated only in crew members who landed in Russia, probably because of the longer time lapse between landing and sample collection. These data provide evidence that bone loss, compromised vitamin D status, and oxidative damage remain critical concerns for long-duration space flight.
    Keywords: Aerospace Medicine
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  • 5
    Publication Date: 2019-07-13
    Description: Bone loss is a current limitation for long-term space exploration. Bone markers, calcitropic hormones, and calcium kinetics of crew members on space missions of 4-6 months were evaluated. Spaceflight-induced bone loss was associated with increased bone resorption and decreased calcium absorption. INTRODUCTION: Bone loss is a significant concern for the health of astronauts on long-duration missions. Defining the time course and mechanism of these changes will aid in developing means to counteract these losses during space flight and will have relevance for other clinical situations that impair weight-bearing activity. MATERIALS AND METHODS: We report here results from two studies conducted during the Shuttle-Mir Science Program. Study 1 was an evaluation of bone and calcium biochemical markers of 13 subjects before and after long-duration (4-6 months) space missions. In study 2, stable calcium isotopes were used to evaluate calcium metabolism in six subjects before, during, and after flight. Relationships between measures of bone turnover, biochemical markers, and calcium kinetics were examined. RESULTS: Pre- and postflight study results confirmed that, after landing, bone resorption was increased, as indicated by increases in urinary calcium (p 〈 0.05) and collagen cross-links (N-telopeptide, pyridinoline, and deoxypyridinoline were all increased 〉55% above preflight levels, p 〈 0.001). Parathyroid hormone and vitamin D metabolites were unchanged at landing. Biochemical markers of bone formation were unchanged at landing, but 2-3 weeks later, both bone-specific alkaline phosphatase and osteocalcin were significantly (p 〈 0.01) increased above preflight levels. In studies conducted during flight, bone resorption markers were also significantly higher than before flight. The calcium kinetic data also validated that bone resorption was increased during flight compared with preflight values (668 +/- 130 versus 427 +/- 153 mg/day; p 〈 0.001) and clearly documented that true intestinal calcium absorption was significantly lower during flight compared with preflight values (233 +/- 87 versus 460 +/- 47 mg/day; p 〈 0.01). Weightlessness had a detrimental effect on the balance in bone turnover such that the daily difference in calcium retention during flight compared with preflight values approached 300 mg/day (-234 +/- 102 versus 63 +/- 75 mg/day; p 〈 0.01). CONCLUSIONS: These bone marker and calcium kinetic studies indicated that the bone loss that occurs during space flight is a consequence of increased bone resorption and decreased intestinal calcium absorption.
    Keywords: Aerospace Medicine
    Type: JSC-CN-8528 , Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research (ISSN 0884-0431); 20; 2; 208-18
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  • 6
    Publication Date: 2019-07-13
    Description: Prolonged microgravity exposure disrupts bone, muscle, and cardiovascular homeostasis, sensory-motor coordination, immune function, and behavioral performance. Bone loss, in particular, remains a serious impediment to the success of exploration-class missions by increasing the risks of bone fracture and renal stone formation for crew members. Current countermeasures, consisting primarily of resistive and aerobic exercise, have not yet proven fully successful for preventing bone loss during long-duration spaceflight. While other bone-specific countermeasures, such as pharmacological therapy and dietary modifications, are under consideration, countermeasure approaches that simultaneously address multiple physiologic systems may be more desirable for exploration-class missions, particularly if they can provide effective protection at reduced mission resource requirements (up-mass, power, crew time, etc). The most robust of the multi-system approaches under consideration, artificial gravity (AG), could prevent all of the microgravity-related physiological changes from occurring. The potential methods for realizing an artificial gravity countermeasure are reviewed, as well as selected animal and human studies evaluating the effects of artificial gravity on bone function. Future plans for the study of the multi-system effects of artificial gravity include a joint, cooperative international effort that will systematically seek an optimal prescription for intermittent AG to preserve bone, muscle, and cardiovascular function in human subjects deconditioned by 6 degree head-down-tilt-bed rest. It is concluded that AG has great promise as a multi-system countermeasure, but that further research is required to determine the appropriate parameters for implementation of such a countermeasure for exploration-class missions.
    Keywords: Aerospace Medicine
    Type: Bone Loss During Space Flight; Jun 23, 2005 - Jun 24, 2005; Cleveland, OH; United States
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  • 7
    Publication Date: 2019-08-14
    Description: No abstract available
    Keywords: Aerospace Medicine
    Type: Aviation, space, and environmental medicine (ISSN 0095-6562); 76; 6 Suppl; B1-2
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  • 8
    Publication Date: 2019-07-13
    Description: BACKGROUND: Exercise is a promising countermeasure to the physiological deconditioning experienced in microgravity, but has not proven effective in eliminating the ongoing loss of bone mineral, most likely due to the lack of high-impact forces and loading rates during in-flight activity. We wanted to determine lower-extremity response to high-impact jumping exercises in true and simulated microgravity and establish if 1-G force magnitudes can be achieved in a weightless environment. METHODS: Jumping experiments were performed in a ground-based zero-gravity simulator (ZGS) in 1 G, and during parabolic flight with a gravity-replacement system. There were 12 subjects who participated in the study, with 4 subjects common to both conditions. Force, loading rates, jump height, and kinematics were analyzed during jumps with three distinct landings: two-footed toe-heel, one-footed toe-heel, and flat-footed. Gravity replacement loads of 45%, 60%, 75%, and 100% bodyweight were used in the ZGS; because of time constraints, these loads were limited to 60% and 75% bodyweight in parabolic flight. RESULTS: Average peak ground-reaction forces during landing ranged between 1902+/-607 and 2631+/-663 N in the ZGS and between 1683+/-807 and 2683+/-1174 N in the KC-135. No significant differences were found between the simulated and true microgravity conditions, but neither condition achieved the magnitudes found in 1 G. CONCLUSION: Data support the hypothesis that jumping exercises can impart high-impact forces during weightlessness and that the custom-designed ZGS will replicate what is experienced in true microgravity.
    Keywords: Aerospace Medicine
    Type: Aviation, space, and environmental medicine (ISSN 0095-6562); 76; 5; 441-7
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