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This paper describes a steady numerical flow model and experimental gas flow results of a self-encapsulated, piezoelectrically actuated, cryogenic micro-valve for distributed cooling applications. Experimental flow data of the prototype micro-valve design is obtained for various gases at room temperature and for helium at near liquid nitrogen temperature. With a pressure differential of 100 kPa across the inlet and outlet, a prototype micro-valve is shown to modulate the flow of room temperature helium from 1200 to 0 sccm. Numerical flow results and experimental data agree well, with 60% of the data points falling within the range of ±10%.

Future mission planning within NASA has increasingly motivated consideration of cryogenic propellant storage durations on the order of years as opposed to a few weeks or months. Furthermore, the advancement of cryocooler and passive insulation technologies in recent years has substantially improved the prospects for zero boiloff storage of cryogenics. Accordingly, a cooperative effort by NASA's Ames Research Center (ARC), Glenn Research Center (GRC), and Marshall Space Flight Center (MSFC) has been implemented to develop and demonstrate "zero boiloff" concepts for in-space storage of cryogenic propellants, particularly liquid hydrogen and oxygen. ARC is leading the development of flight-type cryocoolers, GRC the subsystem development and small scale testing, and MSFC the large scale and integrated system level testing. Thermal and fluid modeling involves a combined effort by the three Centers. Recent accomplishments include: 1) development of "zero boiloff" analytical modeling techniques for sizing the storage tankage, passive insulation, cryocooler, power source mass, and radiators; 2) an early subscale demonstration with liquid hydrogen 3) procurement of a flight-type 10 watt, 95 K pulse tube cryocooler for liquid oxygen storage and 4) assembly of a large-scale test article for an early demonstration of the integrated operation of passive insulation, destratification/pressure control, and cryocooler (commercial unit) subsystems to achieve zero boiloff storage of liquid hydrogen. Near term plans include the large-scale integrated system demonstration testing this summer, subsystem testing of the flight-type pulse-tube cryocooler with liquid nitrogen (oxygen simulant), and continued development of a flight-type liquid hydrogen pulse tube cryocooler.

Current studies within NASA involve extending the human exploration of space from low earth orbit into the solar system, with the first human exploration of Mars proposed in 2014. The key cryogenic technology areas to be addressed in human Mars missions are long-term propellant storage, cryogenic refrigeration, cryogenic liquefaction, and zero gravity fluid management. Passive technologies such as advanced multilayer insulation (MLI) concepts, vapor-cooled shields (VCS), and catalytic converters will be combined with the development of active coolers (cryogenic refrigerators). The integration of passive and active technologies will form a hybrid system optimized to minimize the launch mass while preserving the cryogenic propellants. This paper will present a brief overview of the proposed Mars reference mission and the concomitant cryogenic fluid management technology, focusing on active cooling technology.

The thermal conductance of pressed contacts which have been augmented with indium foil or Apiezon-N™ grease has been measured over the temperature range 1.6–6.0 K, with applied forces from 22 to 670N. The sample pairs were fabricated from OFHC copper, 6061-T6 aluminium, free-machining brass and 304 stainless steel. Although the thermal conductance was found to increase with increasing applied contact force, the force dependence was less than in earlier work. The addition of indium foil or Apiezon grease between the contact surfaces resulted in an improvement over uncoated surfaces ranging from approximately a factor of 3 for stainless steel to an order of magnitude for copper contacts.

The thermal conductance of one aluminum and one stainless steel pressed metal contacts has been measured near 77 K, with applied forces from 8.9 N to 267 N. Both 5052 or 5083 aluminum were used as the upper contact. The lower contact was 304L stainless steel. The thermal conductance is linear in temperature over the range of measurement and ranged from roughly 9 to 21 mW/K. There is no difference in conductance between the two aluminum alloys. Extrapolating the data to zero applied force does not result in zero thermal conductance. A possible cause of this anomalous effect is discussed.

The thermal conductance of uncoated oxygen-free high conductivity (OFHC) copper, 6061-T6 aluminum, free-machining brass, and 304 stainless steel sample pairs which were augmented with a gold coated 6061-T6 aluminum washer inserted between the contact surfaces was measured over the temperature range of 1.6 to 6.0 K, with applied forces from 22 to 670 N. The contact surfaces of the sample pairs were prepared with a 0.8 micron lapped finish, while the finish of the aluminum washer was 0.2 micron lapped. The contribution to the overall thermal impedance by the bulk conductance of the aluminum washer was negligible. It was found that addition of the washer offered no significant conductance improvement over an uncoated single contact pair; any benefits from using the gold plated washer were counteracted by the addition of two more contact surfaces. Additionally, the thermal conductance of a 'combination' aluminum sample pair having one gold coated and one uncoated surface was measured and compared to the washer pair. The ratio of the conductance of the washer pair to half the conductance of the 'combination' pair was found to be constant and near unity over the temperature range of the data obtained, within experimental error.

In support of the U.S. Space Exploration Policy, focused cryogenic fluid management technology efforts are underway within the National Aeronautics and Space Administration. Under the auspices of the Exploration Technology Development Program, cryogenic fluid management technology efforts are being conducted by the Cryogenic Fluid Management Project. Cryogenic Fluid Management Project objectives are to develop storage, transfer, and handling technologies for cryogens to support high performance demands of lunar, and ultimately, Mars missions in the application areas of propulsion, surface systems, and Earth-based ground operations. The targeted use of cryogens and cryogenic technologies for these application areas is anticipated to significantly reduce propellant launch mass and required on-orbit margins, to reduce and even eliminate storage tank boil-off losses for long term missions, to economize ground pad storage and transfer operations, and to expand operational and architectural operations at destination. This paper organizes Cryogenic Fluid Management Project technology efforts according to Exploration Architecture target areas, and discusses the scope of trade studies, analytical modeling, and test efforts presently underway, as well as future plans, to address those target areas. The target areas are: liquid methane/liquid oxygen for propelling the Altair Lander Ascent Stage, liquid hydrogen/liquid oxygen for propelling the Altair Lander Descent Stage and Ares V Earth Departure Stage, liquefaction, zero boil-off, and propellant scavenging for Lunar Surface Systems, cold helium and zero boil-off technologies for Earth-Based Ground Operations, and architecture definition studies for long term storage and on-orbit transfer and pressurization of LH2, cryogenic Mars landing and ascent vehicles, and cryogenic production via in situ resource utilization on Mars.

In future space applications, large and distributed loads will require active thermal control if their lifetimes are to be extended beyond one or two years. Examples include Zero Boil-Off (ZBO) cryogenic systems for exploration missions, and cooling of widely distributed sensor arrays and large deployable structures, such as mirrors and sunshades, for space science missions. These applications will require efficient means of heat transfer from extended structures or from several discrete elements to one or more remotely located heat rejection packages consisting of active and passive components. More or less stringent temperature control will also be required. We have recently undertaken a program to develop a number of technologies relevant to the issues associated with distributed cooling. These include circulation networks that transfer heat via steady flows of cold pressurized gas; gas rectifiers for use with linear pressure wave generators; and MEMS-based throttling valves for precise temperature control. This paper describes the studies that are underway to establish the performance potential of each.

This paper reports on a drug delivery system that provides modulated delivery of liquid-phase chemicals. The device uses silicon torsion springs on a 2times3 cm2 chip to pressurize a soft polymeric reservoir and regulate flow with a piezoelectricaly actuated silicon microvalve that is 1.5times1.5times1 cm3. Using the finished device, regulated diffusion of a fluorescent dye into agar gel was demonstrated. Fluid flow out of the 500 muL reservoir could be regulated from 10-500 muL/min with up to 80 kPa of delivery pressure. Typical regulation consumes 0.136 muW of power. Analysis of the valve, reservoir springs, and a model based on pressure-enhanced diffusion are presented and are validated by experimental data.

This paper describes a normally open, self-encapsulated, gas valve that has embedded sensors for pressure and temperature monitoring. The valve has been validated at operating temperatures over 80-380 K, and at pressures up to 130 kPa. A perimeter augmentation scheme for the valve seat has been implemented to provide higher flow modulation. Two kinds of suspensions are described for the valve seat. In tests performed at room temperature, the flow was modulated from 980 mL/min. with the valve fully open (0 V), to 0 mL/min. with 60 V actuation, at an inlet pressure of 55 kPa. Cryogenic flow rate tests show similar modulation with flow from 166 mL/min. with the valve fully open, to 5.3 mL/min. with 120 V actuation voltage, at an inlet pressure of 70 kPa. The platinum RTD temperature sensor is independently tested from 40-450 K with sensitivity of 0.23 %/K in its operational range of 150- 450 K. The pressure sensor has sensitivity of 250 ppm/kPa at room temperature.

A lightweight, high efficiency cryocooler has been tested. The design operating point of the cooler is 10 W at 95 K with a rejection temperature of 300 K, and the goal is a 10 yr operating lifetime. The cooler has a mass of less than 4.0 kg. The cooler efficiency at the design operating point is 12.6 W/W. These values represent approximately a one-third decrease in mass and a one-third increase in efficiency over previous designs.

Storing cryogenic propellants with zero boil off (ZBO) using a combination of active (cryocoolers) and passive technologies has recently received a great deal of attention for longterm space missions. This paper will examine a variety of potential near-term terrestrial applications for ZBO and, where appropriate, provide a rough order of magnitude cost benefit of implementing ZBO technology.

New materials are being designed to allow the implementation of innovative concepts in future space transportation vehicles. In present day spacecraft, launch vehicles consist of an overall structure in which the cryogenic propellant tanks are mounted in a framework covered by an aeroshell. In NASA s next generation space transportation vehicles the innovative concept of conformal propellant tanks will be utilized. In addition to containing the propellants the cryogen tanks will serve as part of the main vehicle structure. This concept enables significant reduction in launch mass. Crucial to this approach will be the development of a material that will serve not only as cryogenic insulation on the launchpad and early in flight, but also as a thermal protection system (TPS), protecting the vehicle on re-entry. Prior to selection for this challenging application various material properties are to be assessed. The present paper discusses experimental results on the thermal conductivity of a preliminary candi...

This paper reports on a normally open piezoelectrically actuated microvalve for high flow modulation at cryogenic temperatures. One application envisioned is to control the flow of a cryogen for distributed cooling with a high degree of temperature stability and a small thermal gradient. The valve consists of a micromachined die fabricated from a silicon-on-insulator wafer, a glass wafer, a commercially available piezoelectric stack actuator and Macor™ ceramic encapsulation that has overall dimensions of 1 × 1 × 1 cm3. A perimeter augmentation scheme for the valve seat has been implemented to provide high flow modulation. In tests performed at room temperature the flow was modulated from 980 mL min−1with the valve fully open (0 V), to 0 mL min−1with a 60 V actuation voltage, at an inlet gauge pressure of 55 kPa. This range is orders of magnitude higher flow than the modulation capability of similarly sized piezoelectric microvalves. At the cryogenic temperature of 80 K, the valve successfully modulated gas flow from 350 mL min−1down to 20 mL min−1with an inlet pressure of 104 kPa higher than the atmosphere. The operation of this valve has been validated at elevated temperatures as well, up to 380 K. The valve has a response time of less than 1 ms and has operational bandwidth up to 820 kHz.

Pupil Control Ideology is expressed in terms of a custodial‐humanistic continuum. A cutodial orientation stresses the maintenance of order through strong discipline and punitive sanctions; a humanistic orientation emphasizes trust and optimism concerning students' ability to be self‐disciplining. Pluralistic ignorance is defined as the shared misperception of an attitude, norm or belief held by members of a group. 296 faculty members from 17 elementary and two high schools in a single school district completed three versions of the PCI form and a sociometric scale. Findings mealedinter aliathat there were positive relationships between the individual teacher's PCI and his perception of the PCI both of members of his informal group and teachers in the school district. Individual teachers also perceived the PCI of the typical teacher in the district to be more custodial than his actual PCI. Although perceptions of the PCI of members in the informal group were also more custodial than actual measurements indicated, such perceptions were more accurate.

Etude experimentale de la resistance thermique de contact de surfaces de cuivre avec un fini de surface de 0,4 micron entre 1,6 et 4,2°K pour des forces de pression allant jusqu'a 670 N. Etablissement d'une correlation

(1959). Hypochromic Anemia of Pregnancy. Postgraduate Medicine: Vol. 25, No. 6, pp. 761-768.

1. 1. One hundred and thirty-two cases of combined feminizing tumors of the ovary and carcinoma of the uterus were reviewed from the literature. 2. 2. Twenty-eight new cases of feminizing mesenchymoma of the ovary were reported. Eight cases of combined carcinoma and granulosa cell tumor were presented and evaluated. 3. 3. Evidence is offered that granulosa cell tumors, as well as thecomas, present a clinical and pathologic picture of hyperestrogenism. 4. 4. The relationship of estrogen to carcinogenesis in certain target or “receptor” tissues is discussed.

Two all-metal demountable cryogenic seals with an outside diameter of 36.6 mm, inside diameter of 27.2 mm and thickness of 0.51 mm were leak-tested at room temperature (300 K), liquid nitrogen temperature (21 cycles at 77 K), liquid helium temperature (nine cycles at 4.2K) and superfluid helium temperature (four cycles at 1.6 K). Each seal was mounted and demounted for 13 cycles. Thickness measurements at 90 deg intervals along the circumference showed a maximum seal compression of 0.038 mm. Leak rate measurements at all temperatures showed no detectable leak above the helium background level, typically 0.1 x 10 exp -9 std cu cm/s, during testing.

The thermal conductance of pairs of oxygen-free high conductivity (OFHC) copper specimens with surface finishes ranging from 0.1 to 1.6-μm rms roughness has been investigated over the range of 1.6 to 6.0-K under applied contact forces up to 670 N. The thermal conductance increases with increasing contact force; however, no correlation can be drawn with respect to surface finish.

A concept is presented for a national cryogenic optics test facility capable of optical characterization of 1.25 m diameter optics having focal lengths up to 6.2 m at temperatures from 300 K to near 4 K. The facility will be comprised of a large Dewar with a phase shift interferometer, a two stage vacuum system employing a turbomolecular pump, and an integral vibration isolation system. The entire facility will be housed in a concrete site with a massive floor to assist in reducing vibration during optical tests. By providing interchangeable sections, the overall height of the Dewar can be adjusted to provide for testing of shorter focal length optics. The background for the facility is discussed along with the facility location, and the requirements and the performance considerations which drive the Dewar design with respect to the vibration isolation system, vacuum system, and optical interferometry.

The thermal contact conductance of a 0.4 micrometer surface finish OFHC copper sample pair has been investigated from 1.6 to 3.8 K for a range of applied contact forces up to 670 N. Experimental data have been fitted to the relation Q = the integral alpha T to the nth power dt by assuming that the thermal contact conductance is a simple power function of the sample temperature. It has been found that the conductance is proportional to T squared and that conductance increases with an increase in applied contact force. These results confirm earlier work.

It is estimated that there are 25,000 female addicts in the Metropolitan area of New York City. As a consequence, we are faced with a significant number of pregnant addicts. Our study of over 300 such patients demonstrates the problems they present. Over 90 per cent of these women had no or inadequate prenatal care. The incidence of maternal complications has been markedly higher than in our general clinic population. Obstetric complications include prematurity, toxemia, breech births, and precipitate labor. As might be expected, prostitution serves as the source of income to support the drug habit, and the incidence of venereal disease and hepatitis is increased. Over 70 per cent of the neonates show congenital neonatal addiction with clinically recognizable withdrawal symptoms. These symptoms suggest hyperactivity of the autonomic nervous system as evidenced by diaphoresis, diarrhea, and rhinorrhea. Hypertonicity and a characteristic high-pitched shrill cry are frequently observed. In addition to being premature by dates, 50 per cent of these infants show evidence of retarded intrauterine growth. The severity of the symptoms seems to be maternal dose related.

Summary Three thousand eleven pregnancieswere followed from presentation to post-partum period, for determination of the incidences of Rh negativity and of hemolytic disease of the newborn. Rh testing and adequate diagnostic measures applied to the offspring of these mothers were employed. In this group, a mixed white, Negro, and Puerto Rican group, accurate figures on the incidence of Rh negativity were obtained. Only nine cases of hemolytic disease were detected, of which two were stillbirths. The latter were the only deaths.

Introduction DESPITE the relatively great advances made in prenatal care during the past several decades, preeclampsia and the other toxemias of pregnancy remain a serious obstetrical problem. In fact, toxemia is at present one of the three leading causes of fetal and maternal mortality, together with infection and hemorrhage. 1 This study was designed to add data pertinent to the theory that preeclampsia might be a psychophysiologic illness. Our working hypothesis was that there may exist significant psychologic factors in patients who develop preeclampsia which contribute to the precipitating or sustaining of this serious complication of pregnancy. In reviewing the literature, the possibility that psychologic factors might play a role in the toxemias of pregnancy has been suggested in the past. For example, after studying toxemia in various parts of the world, Dieckmann stated in 1946 that, "our data seem to indicate that toxemia